Name: genetic incorporation of biosynthesized l-dihydroxyphenylalanine (dopa) and its application to protein conjugation
Uploaded: 2018-08-24T15:00:00
Description: Watch this Scientific Journal Video about Genetic Incorporation of Biosynthesized L-dihydroxyphenylalanine DOPA and Its Application to Protein Conjugation at JoVE.com

This research was supported by the Global Frontier Research Program (NRF-2015M3A6A8065833), and the Basic Science&#160;Research Program (2018R1A6A1A03024940)&#160;through the National Research Foundation of Korea (NRF) funded&#160;by the Korea government.&#160;

1. Plasmid Construction
<ol>
	<li>Construct an expression plasmid (pBAD-dual-TPL-GFP-WT) that expresses the TPL gene from Citrobacter freundii under the control of a constitutive promoter and the green fluorescent protein (GFP) gene with a His6-tag under the control of the araBAD promoter. For pBAD-dual-TPL-GFP-E90TAG, replace the codon for the site (E90) of DOPA with an amber codon (TAG), using a site-directed mutagenesis protocol. The details for the construction of this plasmid was described in o...

<ol>
	<li>Nagatsu, T., Levitt, M., Udenfriend, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tyrosine+hydroxylase:+The+initial+step+in+norepinephrine+biosynthesis.">Tyrosine hydroxylase: The initial step in norepinephrine biosynthesis.</a> Journal of Biological Chemistry. 239, 2910-2917 (1964).</li><li>Pinder, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Possible+dopamine+derivatives+capable+of+crossing+the+blood-brain+barrier+in+relation+to+parkinsonism.">Possible dopamine derivatives capable of crossing the blood-brain barrier in relation to parkinsonism.</a> Nature. 228 (5269), 358 (1970).</li><li>Waite, J. H., Tanzer, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyphenolic+substance+of+mytilus+edulis:+novel+adhesive+containing+L-DOPA+and+hydroxyproline.">Polyphenolic substance of mytilus edulis: novel adhesive containing L-DOPA and hydroxyproline.</a> Science. 212 (4498), 1038-1040 (1981).</li><li>Lee, H., Scherer, N. F., Messersmith, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-molecule+mechanics+of+mussel+adhesion.">Single-molecule mechanics of mussel adhesion.</a> Proceedings of the National Academy of Sciences of the United States of America. 103 (35), 12999-13003 (2006).</li><li>Papov, V. V., Diamond, T. V., Biemann, K., Waite, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydroxyarginine-containing+polyphenolic+proteins+in+the+adhesive+plaques+of+the+marine+mussel+Mytilus+edulis.">Hydroxyarginine-containing polyphenolic proteins in the adhesive plaques of the marine mussel Mytilus edulis.</a> Journal of Biological Chemistry. 270 (34), 20183-20192 (1995).</li><li>Waite, J. H., Qin, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyphosphoprotein+from+the+adhesive+pads+of+Mytilus+edulis.">Polyphosphoprotein from the adhesive pads of Mytilus edulis.</a> Biochemistry. 40 (9), 2887-2893 (2001).</li><li>Nicklisch, S. C., Waite, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mini-review:+The+role+of+redox+in+DOPA-mediated+marine+adhesion.">Mini-review: The role of redox in DOPA-mediated marine adhesion.</a> Biofouling. 28 (8), 865-877 (2012).</li><li>Silverman, H. G., Roberto, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+marine+mussel+adhesion.">Understanding marine mussel adhesion.</a> Marine Biotechnology. 9 (6), 661-681 (2007).</li><li>Lee, B. P., Messersmith, P. B., Israelachvili, J. N., Waite, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mussel-inspired+adhesives+and+coatings.">Mussel-inspired adhesives and coatings.</a> Annual Review of Materials Research. 41, 99-132 (2011).</li><li>Umeda, A., Thibodeux, G. N., Zhu, J., Lee, Y., Zhang, Z. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Site-specific+protein+cross-linking+with+genetically+incorporated+3,4-dihydroxy-L-phenylalanine.">Site-specific protein cross-linking with genetically incorporated 3,4-dihydroxy-L-phenylalanine.</a> ChemBioChem. 10 (8), 1302-1304 (2009).</li><li>Umeda, A., Thibodeux, G. N., Moncivais, K., Jiang, F., Zhang, Z. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+versatile+approach+to+transform+low-affinity+peptides+into+protein+probes+with+cotranslationally+expressed+chemical+cross-linker.">A versatile approach to transform low-affinity peptides into protein probes with cotranslationally expressed chemical cross-linker.</a> Analytical Biochemistry. 405 (1), 82-88 (2010).</li><li>Xu, J., Tack, D., Hughes, R. A., Ellington, A. D., Gray, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure-based+non-canonical+amino+acid+design+to+covalently+crosslink+an+antibody-antigen+complex.">Structure-based non-canonical amino acid design to covalently crosslink an antibody-antigen complex.</a> Journal of Structural Biology. 185 (2), 215-222 (2014).</li><li>Burdine, L., Gillette, T. G., Lin, H. J., Kodadek, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Periodate-triggered+cross-linking+of+DOPA-containing+peptide-protein+complexes.">Periodate-triggered cross-linking of DOPA-containing peptide-protein complexes.</a> Journal of the American Chemical Society. 126 (37), 11442-11443 (2004).</li><li>Borrmann, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strain-promoted+oxidation-controlled+cyclooctyne-1,2-quinone+cycloaddition+(SPOCQ)+for+fast+and+activatable+protein+conjugation.">Strain-promoted oxidation-controlled cyclooctyne-1,2-quinone cycloaddition (SPOCQ) for fast and activatable protein conjugation.</a> Bioconjugate Chemistry. 26 (2), 257-261 (2015).</li><li>Ayyadurai, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+selective,+sensitive,+and+reversible+biosensor+by+the+genetic+incorporation+of+a+metal-binding+site+into+green+fluorescent+protein.">Development of a selective, sensitive, and reversible biosensor by the genetic incorporation of a metal-binding site into green fluorescent protein.</a> Angewandte Chemie International Edition. 50 (29), 6534-6537 (2011).</li><li>Kim, B. J., Cheong, H., Hwang, B. H., Cha, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mussel-inspired+protein+nanoparticles+containing+iron(III)-DOPA+complexes+for+pH-responsive+drug+delivery.">Mussel-inspired protein nanoparticles containing iron(III)-DOPA complexes for pH-responsive drug delivery.</a> Angewandte Chemie International Edition. 54 (25), 7318-7322 (2015).</li><li>Alfonta, L., Zhang, Z., Uryu, S., Loo, J. A., Schultz, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Site-specific+incorporation+of+a+redox-active+amino+acid+into+proteins.">Site-specific incorporation of a redox-active amino acid into proteins.</a> Journal of the American Chemical Society. 125 (48), 14662-14663 (2003).</li><li>Kim, S., Sung, B. H., Kim, S. C., Lee, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+incorporation+of+L-dihydroxyphenylalanine+(DOPA)+biosynthesized+by+a+tyrosine+phenol-lyase.">Genetic incorporation of L-dihydroxyphenylalanine (DOPA) biosynthesized by a tyrosine phenol-lyase.</a> Chemical Communications. 54 (24), 3002-3005 (2018).</li><li>Young, T. S., Ahmad, I., Yin, J. A., Schultz, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+enhanced+system+for+unnatural+amino+acid+mutagenesis+in+E.+coli.">An enhanced system for unnatural amino acid mutagenesis in E. coli.</a> Journal of Molecular Biology. 395 (2), 361-374 (2010).</li><li>Studier, F. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+production+by+auto-induction+in+high+density+shaking+cultures.">Protein production by auto-induction in high density shaking cultures.</a> Protein Expression and Purification. 41 (1), 207-234 (2005).</li><li>Bradford, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid+and+sensitive+method+for+the+quantitation+of+microgram+quantities+of+protein+utilizing+the+principle+of+protein-dye+binding.">A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding.</a> Analytical Biochemistry. 72 (1-2), 248-254 (1976).</li><li>Jang, S., Sachin, K., Lee, H. J., Kim, D. W., Lee, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+simple+method+for+protein+conjugation+by+copper-free+click+reaction+and+its+application+to+antibody-free+Western+blot+analysis.">Development of a simple method for protein conjugation by copper-free click reaction and its application to antibody-free Western blot analysis.</a> Bioconjugate Chemistry. 23 (11), 2256-2261 (2012).</li><li>Gobom, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alpha-cyano-4-hydroxycinnamic+acid+affinity+sample+preparation.+A+protocol+for+MALDI-MS+peptide+analysis+in+proteomics.">Alpha-cyano-4-hydroxycinnamic acid affinity sample preparation. A protocol for MALDI-MS peptide analysis in proteomics.</a> Analytical Chemistry. 73 (3), 434-438 (2001).</li><li>Mukai, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+reproductive+Escherichia+coli+cells+with+no+specific+assignment+to+the+UAG+codon.">Highly reproductive Escherichia coli cells with no specific assignment to the UAG codon.</a> Scientific Reports. 5, 9699 (2015).</li><li>Lajoie, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genomically+recoded+organisms+expand+biological+functions.">Genomically recoded organisms expand biological functions.</a> Science. 342 (6156), 357-360 (2013).</li><li>Bryson, D. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+directed+evolution+of+aminoacyl-tRNA+synthetases.">Continuous directed evolution of aminoacyl-tRNA synthetases.</a> Nature Chemical Biology. 13 (12), 1253-1260 (2017).</li><li>Guo, J., Melancon, C. E., Lee, H. S., Groff, D., Schultz, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+amber+suppressor+tRNAs+for+efficient+bacterial+production+of+proteins+containing+nonnatural+amino+acids.">Evolution of amber suppressor tRNAs for efficient bacterial production of proteins containing nonnatural amino acids.</a> Angewandte Chemie International Edition. 48 (48), 9148-9151 (2009).</li><li>Lee, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+facile+strategy+for+selective+phosphoserine+incorporation+in+histones.">A facile strategy for selective phosphoserine incorporation in histones.</a> Angewandte Chemie International Edition. 52 (22), 5771-5775 (2013).</li><li>Neumann, H., Wang, K., Davis, L., Garcia-Alai, M., Chin, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Encoding+multiple+unnatural+amino+acids+via+evolution+of+a+quadruplet-decoding+ribosome.">Encoding multiple unnatural amino acids via evolution of a quadruplet-decoding ribosome.</a> Nature. 464 (7287), 441-444 (2010).</li><li>Lang, K., Chin, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioorthogonal+reactions+for+labeling+proteins.">Bioorthogonal reactions for labeling proteins.</a> ACS Chemical Biology. 9 (1), 16-20 (2014).</li><li>Lang, K., Chin, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+Incorporation+of+unnatural+amino+acids+and+bioorthogonal+labeling+of+proteins.">Cellular Incorporation of unnatural amino acids and bioorthogonal labeling of proteins.</a> Chemical Reviews. 114 (9), 4764-4806 (2014).</li><li>Plass, T., Milles, S., Koehler, C., Schultz, C., Lemke, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+encoded+copper-free+click+chemistry.">Genetically encoded copper-free click chemistry.</a> Angewandte Chemie International Edition. 50 (17), 3878-3881 (2011).</li><li>Seitchik, J. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+encoded+tetrazine+amino+acid+directs+rapid+site-specific+in+vivo+bioorthogonal+ligation+with+trans-cyclooctenes.">Genetically encoded tetrazine amino acid directs rapid site-specific in vivo bioorthogonal ligation with trans-cyclooctenes.</a> Journal of the American Chemical Society. 134 (6), 2898-2901 (2012).</li></ol>

In this protocol, the biosynthesis and direct incorporation of DOPA are described. The bacterial cell used in this method can synthesize an additional amino acid and use it as an unnatural building block for protein synthesis. The genetic incorporation of unnatural amino acids has been a key technology for the development of unnatural organism with an expanded genetic code. However, this method has been technically incomplete and is being modified to improve incorporation efficiency and minimize perturbation to endogenou...

DOPA is an amino acid involved in the biosynthesis of catecholamines in animals and plants. This amino acid is synthesized from Tyr by tyrosine hydroxylase and molecular oxygen (O2)1. Because DOPA is a precursor of dopamine and can permeate the blood-brain barrier, it has been used in the treatment of Parkinson&#39;s disease2. DOPA is also found in mussel adhesion proteins (MAPs), which are responsible for the adhesive properties of mussels in wet conditions3,4,5,6,7. Tyr is initially encoded at the positions where DOPA is found in MAPs and is then converted into DOPA by tyrosinases8,9. Because of its interesting biochemical properties, DOPA has been used in a variety of applications. The dihydroxyl group of DOPA is chemically prone to oxidation, and the amino acid is easily converted into L-dopaquinone, a precursor of melanins. Owing to its high electrophilicity, L-dopaquinone and its derivatives have been used for crosslinking and conjugation with thiols and amines10,11,12,13. 1,2-Quinones can also function as a diene for cycloaddition reactions and have been used for bioconjugation by strain-promoted oxidation-controlled cyclooctyne-1,2-quinone (SPOCQ) cycloaddition14. In addition, the dihydroxyl group can chelate metal ions such as Fe3+ and Cu2+, and proteins containing DOPA have been utilized for drug delivery and metal ion sensing15,16.
DOPA has been genetically incorporated into proteins by using an orthogonal aminoacyl-tRNA (aa-tRNA) and aminoacyl-tRNA synthetase (aaRS) pair17 and used for protein conjugation and crosslinking10,11,12,13. In this report, experimental results and protocols for the genetic incorporation of DOPA biosynthesized from cheap starting materials and its applications to bioconjugation are described. DOPA is biosynthesized using a TPL and starting from catechol, pyruvate, and ammonia in Escherichia coli. The biosynthesized DOPA is directly incorporated into proteins by expressing an evolved aa-tRNA and aaRS pair for DOPA. In addition, the biosynthesized protein containing DOPA is site-specifically conjugated with a fluorescent probe and crosslinked to produce protein oligomers. This protocol will be useful for protein scientists, to biosynthesize mutant proteins containing DOPA and conjugate the proteins with biochemical probes or drugs for industrial and pharmaceutical applications.

<table border="0" cellpadding="0" cellspacing="0" style="width:1235px;" width="1234">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">1. Plasmid Construction</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">Plasmid pBAD-dual-TPL-GFP-E90TAG</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td>optionally contain the amber stop codon(TAG) at a desired position. Ko, W. et al. Efficient and Site-Specific Antibody Labeling by Strain-promoted Azide-Alkyne Cycloaddition. BKCS. 36 (9), 2352-2354, doi: 10.1002/bkcs.10423, (2015)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Plasmid pEvol-DHPRS2</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td>1. Young, T. S., Ahmad, I., Yin, J. A., and Schultz, P. G. An enhanced system for unnatural amino acid mutagenesis in E. coli. J. Mol. Biol. 395 (2), 361-374, doi: 10.1016/j.jmb.2009.10.030, (2010) 2. Kim, S., Sung, B. H., Kim, S. C., Lee, H. S. Genetic incorporation of l-dihydroxyphenylalanine (DOPA) biosynthesized by a tyrosine phenol-lyase. Chem. Commun. 54 (24), 3002-3005, doi: 10.1039/c8cc00281a (2018).</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">DH10&#946;</td>
			<td style="width:167px;">Invitrogen</td>
			<td style="width:133px;">C6400-03</td>
			<td>Expression Host</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Plasmid Mini-prep kit</td>
			<td style="width:167px;">Nucleogen</td>
			<td style="width:133px;">5112</td>
			<td>200/pack</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Agarose</td>
			<td style="width:167px;">Intron biotechnology</td>
			<td style="width:133px;">32034</td>
			<td>500 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Ethidium bromide</td>
			<td style="width:167px;">Alfa Aesar</td>
			<td style="width:133px;">L07482</td>
			<td>1 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">LB Broth</td>
			<td style="width:167px;">BD Difco</td>
			<td style="width:133px;">244620</td>
			<td>500 g</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:596px;">2. Culture preparation</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:596px;">2.1) Electroporation</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Micro pulser&#160;</td>
			<td style="width:167px;">BIO-RAD</td>
			<td style="width:133px;">165-2100</td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Micro pulser cuvette</td>
			<td style="width:167px;">BIO-RAD</td>
			<td style="width:133px;">165-2089</td>
			<td style="width:339px;">0.1 cm electrode gap, pkg. of 50</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Ampicillin Sodium</td>
			<td style="width:167px;">Wako</td>
			<td style="width:133px;">018-10372</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Chloramphenicol</td>
			<td style="width:167px;">Alfa Aesar</td>
			<td style="width:133px;">B20841</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Agar</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">214230</td>
			<td>500 g</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">SOC medium</td>
			<td style="width:167px;">Sigma</td>
			<td style="width:133px;">S1797</td>
			<td>100 mL</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">3. Expression and Purification of GFP-E90DOPA by biosynthetic system</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;width:596px;">3.1 Expression of GFP-E90DOPA by biosynthetic system</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L(+)-Arabinose, 99%</td>
			<td style="width:167px;">Acros</td>
			<td style="width:133px;">104981000</td>
			<td>100 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Pyrocatechol, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">P1387</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Ammonium sulfate, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">A0943</td>
			<td>500 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">pyruvic acid, 98%</td>
			<td style="width:167px;">Alfa Aesar</td>
			<td style="width:133px;">A13875</td>
			<td>100 g</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;width:596px;">Sodium phosphate dibasic, anhydrous, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">S0891</td>
			<td>1 kg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Potassium phophate, monobasic, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">P1127</td>
			<td>1 kg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Magnesium sulfate, anhydrous, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">M0146</td>
			<td>1 kg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">D(+)-Glucose, anhydrous, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">D0092</td>
			<td>500 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Glycerol, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">G0269</td>
			<td>1 kg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Trace metal mix a5 with co</td>
			<td style="width:167px;">Sigma</td>
			<td style="width:133px;">92949</td>
			<td>25 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Proline, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">P1257</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Phenylalanine, 98.5%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">P1982</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Tryptophane</td>
			<td style="width:167px;">JUNSEI</td>
			<td style="width:133px;">49550-0310</td>
			<td>25 g</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">L-Arginine, 98%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">A1149</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Glutamine, 98%</td>
			<td style="width:167px;">JUNSEI</td>
			<td style="width:133px;">27340-0310</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Asparagine monohydrate, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">A1198</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Methionine</td>
			<td style="width:167px;">JUNSEI</td>
			<td style="width:133px;">73190-0410</td>
			<td>25 g</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">L-Histidine hydrochloride monohydrate, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">H0604</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Threonine, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">T2938</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Leucine</td>
			<td style="width:167px;">JUNSEI</td>
			<td style="width:133px;">87070-0310</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Glycine, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">G0286</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Glutamic acid, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">G0233</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Alanine, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">A1543</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Isoleucine, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">I1049</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Valine, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">V0088</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Serine</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">S2447</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Aspartic acid</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">A1205</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">L-Lysine monohydrochloride, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">L0592</td>
			<td>25 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">3.2 Cell lysis</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Imidazole, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">I0578</td>
			<td>1kg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Sodium phosphate monobasic, 98%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">S0919</td>
			<td>1 kg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Sodium Chloride, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">S2907</td>
			<td>1 kg</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">Ultrasonic Processor - 150 microliters to 150 milliliters</td>
			<td style="width:167px;">SONIC &#38; MATERIALS</td>
			<td style="width:133px;">VCX130</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">3.3 Ni-NTA Affinity Chromatography</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Ni-NTA resin</td>
			<td style="width:167px;">QIAGEN</td>
			<td style="width:133px;">30210</td>
			<td>25 mL</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">Polypropylene column</td>
			<td style="width:167px;">QIAGEN</td>
			<td style="width:133px;">34924</td>
			<td>50/pack, 1 mL capacity</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;width:596px;">4. Oligomerization of Purified GFP-E90DOPA&#160;</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">Sodium periodate, 99.8&#38;</td>
			<td style="width:167px;">Acros</td>
			<td style="width:133px;">419610050</td>
			<td>5 g</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;width:596px;">5. Conjugation of GFP-E90DOPA with an Alkyne Probe by Strain-Promoted Oxidation-Controlled Cyclooctyne&#8211;1,2-Quinone Cycloaddition (SPOCQ)&#160;</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">Cy5.5-ADIBO&#160;</td>
			<td style="width:167px;">FutureChem</td>
			<td style="width:133px;">FC-6119</td>
			<td>1mg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">6. Purification of Labeled GFP</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">Amicon Ultra 0.5 mL Centrifugal Filters</td>
			<td style="width:167px;">MILLIPORE</td>
			<td style="width:133px;">UFC500396</td>
			<td>96/pack, 500ul capacity</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">7. SDS-PAGE Analysis and Fluorescence Gel Scanning</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">1,4-Dithio-DL-threitol, DTT, 99.5 %</td>
			<td style="width:167px;">Sigma</td>
			<td style="width:133px;">10708984001</td>
			<td>10 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">NuPAGE LDS Sample Buffer, 4X</td>
			<td style="width:167px;">Thermofisher</td>
			<td style="width:133px;">NP0007</td>
			<td>10 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">MES running buffer</td>
			<td style="width:167px;">Thermofisher</td>
			<td style="width:133px;">NP0002</td>
			<td>500 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Nupage Novex 4-12% SDS PAGE gels</td>
			<td style="width:167px;">Thermofisher</td>
			<td style="width:133px;">NO0321</td>
			<td>12 well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Coomassie Brilliant Blue R-250</td>
			<td style="width:167px;">Wako</td>
			<td style="width:133px;">031-17922</td>
			<td>25 g</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">G:BOX Chemi Fluorescent &#38; Chemiluminescent Imaging System</td>
			<td style="width:167px;">Syngene</td>
			<td style="width:133px;"></td>
			<td>G BOX Chemi XT4</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;width:596px;">8. MALDI-TOF MS analysis by Trypsin Digestion</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;width:596px;">8.1 Preparation of the digested peptide sample by trypsin digestion</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Tris(hydroxymethyl)aminomethane, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">T1351</td>
			<td>500 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Hydrochloric acid, 35~37%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">H0256</td>
			<td>500 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Dodecyl sulfate sodium salt, 85%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">D1070</td>
			<td>250 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Iodoacetamide</td>
			<td style="width:167px;">Sigma</td>
			<td style="width:133px;">I6125</td>
			<td>5 g</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:596px;">Trypsin Protease, MS Grade</td>
			<td style="width:167px;">Thermofisher</td>
			<td style="width:133px;">90057</td>
			<td>5 x 20 &#181;g/pack</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">C-18 spin columns</td>
			<td style="width:167px;">Thermofisher</td>
			<td style="width:133px;">89870</td>
			<td>25/pack, 200 &#181;L capacity</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:21px;width:596px;">8.2 Analysis of the digested peptide by MALDI-TOF</td>
			<td style="width:167px;"></td>
			<td style="width:133px;"></td>
			<td style="width:339px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Acetonitirile, 99.5%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">A0125</td>
			<td>500 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">&#945;-Cyano-4-hydroxycinnamic acid</td>
			<td style="width:167px;">Sigma</td>
			<td style="width:133px;">C2020</td>
			<td>10 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Trifluoroacetic acid, 99%</td>
			<td style="width:167px;">SAMCHUN</td>
			<td style="width:133px;">T1666</td>
			<td>100 g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">MTP 384 target plate ground steel BC targets</td>
			<td style="width:167px;">Bruker</td>
			<td style="width:133px;">8280784</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:596px;">Bruker Autoflex Speed MALDI-TOF mass spectrometer</td>
			<td style="width:167px;">Bruker</td>
			<td style="width:133px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

genetic incorporation of biosynthesized l-dihydroxyphenylalanine (dopa) and its application to protein conjugation

L-dihydroxyphenylalanine (DOPA) is an amino acid found in the biosynthesis of catecholamines in animals and plants. Because of its particular biochemical properties, the amino acid has multiple uses in biochemical applications. This report describes a protocol for the genetic incorporation of biosynthesized DOPA and its application to protein conjugation. DOPA is biosynthesized by a tyrosine phenol-lyase (TPL) from catechol, pyruvate, and ammonia, and the amino acid is directly incorporated into proteins by the genetic incorporation method using an evolved aminoacyl-tRNA and aminoacyl-tRNA synthetase pair. This direct incorporation system efficiently incorporates DOPA with little incorporation of other natural amino acids and with better protein yield than the previous genetic incorporation system for DOPA. Protein conjugation with DOPA-containing proteins is efficient and site-specific and shows its usefulness for various applications. This protocol provides protein scientists with detailed procedures for the efficient biosynthesis of mutant proteins containing DOPA at desired sites and their conjugation for industrial and pharmaceutical applications.

The expression system for the direct incorporation of DOPA biosynthesized from a TPL is shown in Figure 1. The genes for the evolved aa-tRNA and aaRS pair are placed in a plasmid, and the GFP gene (GFP-E90TAG) containing an amber codon at position 90 is located in another plasmid to evaluate the incorporation of DOPA by GFP fluorescence. The TPL gene is placed in the same expression plasmid containing the GFP gene and constitutively expressed to maximize the ...

Watch this Scientific Journal Video about Genetic Incorporation of Biosynthesized L-dihydroxyphenylalanine DOPA and Its Application to Protein Conjugation at JoVE.com

Genetic Incorporation of Biosynthesized L-dihydroxyphenylalanine DOPA and Its Application to Protein Conjugation

Here, we present a protocol for the genetic incorporation of L-dihydroxyphenylalanine biosynthesized from simple starting materials and its application to protein conjugation.

Genetic Incorporation of Biosynthesized L-dihydroxyphenylalanine (DOPA) and Its Application to Protein Conjugation

L-dihydroxyphenylalanine (DOPA) is an amino acid found in the biosynthesis of catecholamines in animals and plants. Because of its particular biochemical ...

This method can help to answer key questions in the chemical biology field, such as protein modification, conjugation, and biosynthetic system. The main advantage of this technique is that L-DOPA can be cited specifically and efficiently introducing the Tyr proteins by using biosynthetic system. After constructing the expression plasmid, set out electrocompetent E.coli DH10 beta strain cells for this procedure.Add one microliter of each plasmid DNA to 20 microliters of competent cells. Use a pipette to gently mix. Transfer this mixture to 0.1 centimeter electroporation cuvettes.Place a filled cuvette in the electroporation chamber, making sure there is firm cuvette chamber contact. Shock the cuvette at 25 microfarad and 2.4 kilovolts. Then, add one milliliter of pre-warmed SOC medium.Transfer the cells to a culture tube. Incubate at 37 degrees Celsius for one hour with shaking to rescue the cells. Spread 10 to 100 microliters of the rescued cells on a lysogeny broth agar plate that contains 35 micrograms per milliliter chloramphenicol and 100 micrograms per milliliter ampicillin.Incubate at 37 degrees Celsius for 16 hours. After this, inoculate a single transformed colony in five milliliters of LB medium containing antibiotics to prepare a starter culture. Incubate at 37 degrees Celsius with shaking for 12 hours.Transfer two milliliters of the starter culture into 100 milliliters of PA-5052 medium, containing chloramphenicol, ampicillin, pyruvate, catechol, ammonia, and dithiothreitol. Incubate at 30 degrees celsius with shaking. When the optical density at 550 nanometers reaches 0.8, add one milliliter of 20%L-arabinose.Incubate the sample at 30 degrees Celsius with shaking for 12 hours. After this, spin down the cells at 11000 times gravity for five minutes. Discard the supernatant and freeze the cell pellet at 80 degrees Celsius until ready to lyse the cells.When ready, thaw the cell pellet on ice. Resuspend the thawed cells in 10 milliliters of lysis buffer containing monosodium phosphate, imidazole, and sodium chloride. Use an 80%sonication amplitude with a pulse of 25 seconds off and 35 seconds off to sonicate the resuspended cells on ice for 10 minutes.Next, spin down the cell lysate at 18000 times gravity at four degrees Celsius for 15 minutes. Transfer the supernatant to a fresh tube for purification and discard the pellet. For a 100 milliliter culture, add 300 microliters of nickel-NTA resin suspension to the collected supernatant.Gently shake the suspension for one hour at four degrees Celsius to bind the proteins to the resin. After this, transfer the suspension to a polypropylene column. Wash the resin three times, using five milliliters of wash buffer for each wash.Then, use 300 microliters of elusion buffer to elute the proteins three times. Determine the protein concentration as outlined in the text protocol. To begin, prepare a 20 microliter solution containing 300 micromolar GFP containing DOPA at position 90 in a phosphate buffer containing 50 millimolar disodium phosphate and 300 millimolar sodium chloride.Add one microliter of a solution containing six millimolar of sodium periodate in water. Let the oligomerization reaction proceed at 25 degrees Celsius for 48 hours. After this, add five microliters of protein sample buffer and two microliters of dithiothreitol to 13 microliters of the oligomerization of GFP in order to prepare the protein samples for SDS page analysis.Incubate at 95 degrees Celsius for 10 minutes to denature the proteins. Next, place a 4%to 12%Bis-Tris SDS page gel cassette in the electrophoresis cell. Add a running buffer to the cassette.Load the protein samples and a molecular weight marker. Run the electrophoresis for 35 to 40 minutes at 200 volts. After this, stain the gel with a commercial protein staining reagent.First, prepare a 20 micromolar solution of GFP containing DOPA at position 90, and a phosphate buffer containing 50 millimolar disodium phosphate and 300 millimolar sodium chloride. Add one microliter of the Cy5.5 linked acid dibenzocyclooctyne. Next, add one microliter of a solution containing 400 micromolar sodium periodate in water to the reaction mixture.Let the strain promoted oxidation controlled cyclooctyne 1, 2-quinone cycloaddition reaction proceed at 25 degrees Celsius for one hour. If a light sensitive probe is used, cover the reaction vessel with aluminum foil. To begin purifying the labeled GFP, dilute the SPOCQ reaction mixture with a phosphate buffer containing 50 millimolar disodium phosphate and 300 millimolar sodium chloride up to 500 microliters.Transfer the diluted solution to a centrifugal filter spin column. Centrifuge the spin column at 14000 times gravity at four degrees Celsius for 15 minutes and discard the flowthrough. First, add five microliters of protein sample buffer and two microliters of dithiothreitol to 13 microliters of purified and labeled GFP in order to prepare the protein samples for SDS-PAGE analysis.Incubate at 95 degrees Celsius for 10 minutes to denature the proteins. Next, place a 4%to 12%Bis-Tris SDS page gel cassette in the electrophoresis cell. Add a running buffer to the cassette.Load the protein samples and a molecular weight marker. Run the electrophoresis for 35 to 40 minutes at 200 volts in the dark. After this, wrap a protein gel and place it on the fluorescence scanner.Use an appropriate wavelength setting to scan the gel. For Cy5.5, select the Cy5 mode provided in the scanning software. Then, stain the gel with a commercial protein staining reagent.In this study, the optimal conditions for DOPA biosynthesis are screened. And the biosynthesized DOPA is directly incorporated into GFP. The expressed mutant, GFP containing DOPA at position 90, is purified and analyzed by SDS-PAGE.The full length GFP is then purified and the DOPA incorporation was confirmed by MALDI-TOF MS analysis. While the incorporation efficiency of biosynthesized DOPA is seen to be similar to the general genetic incorporation efficiency of 3 millimolar DOPA, the cell density after 16 hours of culture is three to fourfold higher. The purified protein yield is also seen to be threefold higher from biosynthesis when compared to the general genetic incorporation.GFP containing DOPA at position 90 is then tested for SPOCQ cycloaddition. An intense fluorescence band is observed when treated with sodium periodate and Cy5.5 ADIBO, while no fluorescence band is seen in control reactions. This confirms the efficiency and specificity of the conjugation reaction with the genetically incorporated DOPA.Lastly, DOPA containing GFP is used for protein oligomerization. A clear oligomerization pattern can be seen with equally spaced protein bands for the periodate treated sample, while the control sample showed the intact protein without any other bands. After its development, this technique paved the way for researchers in the field of chemical biology to explore biochemical applications by L-DOPA containing proteins in a designed model organism.

genetic-incorporation-biosynthesized-l-dihydroxyphenylalanine-dopa

Research

JoVE Journal

Biochemistry

A Protein Preparation Method for the High-throughput Identification of Proteins Interacting with a Nuclear Cofactor Using LC-MS/MS Analysis

Transcriptional coregulators are vital to the efficient transcriptional regulation of nuclear chromatin structure. Coregulators play a variety of roles in regulating transcription. These include the direct interaction with transcription factors, the covalent modification of histones and other proteins, and the occasional chromatin conformation alteration. Accordingly, establishing relatively quick methods for identifying proteins that interact within this network is crucial to enhancing our understanding of the underlying regulatory mechanisms. LC-MS/MS-mediated protein binding partner identification is a validated technique used to analyze protein-protein interactions. By immunoprecipitating a previously-identified member of a protein complex with an antibody (occasionally with an antibody for a tagged protein), it is possible to identify its unknown protein interactions via mass spectrometry analysis. Here, we present a method of protein preparation for the LC-MS/MS-mediated high-throughput identification of protein interactions involving nuclear cofactors and their binding partners. This method allows for a better understanding of the transcriptional regulatory mechanisms of the targeted nuclear factors.

We have established a method for the purification of coregulatory interaction proteins using the LC-MS/MS system.

Transcriptional coregulators are vital to the efficient transcriptional regulation of nuclear chromatin structure. Coregulators play a variety of roles in ...

Preparation of Keratin Hydrolysate from Chicken Feathers and Its Application in Cosmetics

Keratin hydrolysates (KHs) are established standard components in hair cosmetics. Understanding the moisturizing effects of KH is advantageous for skin-care cosmetics. The goals of the protocol are: (1) to process chicken feathers into KH by alkaline-enzymatic hydrolysis and purify it by dialysis, and (2) to test if adding KH into an ointment base (OB) increases hydration of the skin and improves skin barrier function by diminishing transepidermal water loss (TEWL). During alkaline-enzymatic hydrolysis feathers are first incubated at a higher temperature in an alkaline environment and then, under mild conditions, hydrolyzed with proteolytic enzyme. The solution of KH is dialyzed, vacuum dried, and milled to a fine powder. Cosmetic formulations comprising from oil in water emulsion (O/W) containing 2, 4, and 6 weight% of KH (based on the weight of the OB) are prepared. Testing the moisturizing properties of KH is carried out on 10 men and 10 women at time intervals of 1, 2, 3, 4, 24, and 48 h. Tested formulations are spread at degreased volar forearm sites. The skin hydration of stratum corneum (SC) is assessed by measuring capacitance of the skin, which is one of the most world-wide used and simple methods. TEWL is based on measuring the quantity of water transported per a defined area and period of time from the skin. Both methods are fully non-invasive. KH makes for an excellent occlusive; depending on the addition of KH into OB, it brings about a 30% reduction in TEWL after application. KH also functions as a humectant, as it binds water from the lower layers of the epidermis to the SC; at the optimum KH addition in the OB, up to 19% rise in hydration in men and 22% rise in women occurs.

The goal of the protocol is to prepare keratin hydrolysate from chicken feathers by alkaline-enzymatic hydrolysis and to test whether adding keratin hydrolysate into a cosmetics ointment base improves skin barrier function (heightening hydration and diminishing transepidermal water loss). Tests are conducted on men and woman volunteers.

Keratin hydrolysates (KHs) are established standard components in hair cosmetics. Understanding the moisturizing effects of KH is advantageous for ...

High Sensitivity Measurement of Transcription Factor-DNA Binding Affinities by Competitive Titration Using Fluorescence Microscopy

Accurate quantification of transcription factor (TF)-DNA interactions is essential for understanding the regulation of gene expression. Since existing approaches suffer from significant limitations, we have developed a new method for determining TF-DNA binding affinities with high sensitivity on a large scale. The assay relies on the established fluorescence anisotropy (FA) principle but introduces important technical improvements. First, we measure a full FA competitive titration curve in a single well by incorporating TF and a fluorescently labeled reference DNA in a porous agarose gel matrix. Unlabeled DNA oligomer is loaded on the top as a competitor and, through diffusion, forms a spatio-temporal gradient. The resulting FA gradient is then read out using a customized epifluorescence microscope setup. This improved setup greatly increases the sensitivity of FA signal detection, allowing both weak and strong binding to be reliably quantified, even for molecules of similar molecular weights. In this fashion, we can measure one titration curve per well of a multi-well plate, and through a fitting procedure, we can extract both the absolute dissociation constant (KD) and active protein concentration. By testing all single-point mutation variants of a given consensus binding sequence, we can survey the entire binding specificity landscape of a TF, typically on a single plate. The resulting position weight matrices (PWMs) outperform those derived from other methods in predicting in vivo TF occupancy. Here, we present a detailed guide for implementing HiP-FA on a conventional automated fluorescent microscope and the data analysis pipeline.

Here we present a novel method for determining binding affinities at equilibrium and in solution with high sensitivity on a large scale. This improves the quantitative analysis of transcription factor-DNA binding. The method is based on automated fluorescence anisotropy measurements in a controlled delivery system.

Accurate quantification of transcription factor (TF)-DNA interactions is essential for understanding the regulation of gene expression. Since existing ...

Application of Biolayer Interferometry (BLI) for Studying Protein-Protein Interactions in Transcription

A transcription factor&#160;(TF) is a protein that regulates gene expression by interacting with the RNA polymerase, another TF, and/or template DNA. GrgA is a novel transcription activator found specifically in the obligate intracellular bacterial pathogen Chlamydia. Protein pulldown assays using affinity beads have revealed that GrgA binds two &#963; factors, namely &#963;66 and &#963;28, which recognize different sets of promoters for genes whose products are differentially required at developmental stages. We have used BLI to confirm and further characterize the interactions. BLI demonstrates several advantages over pulldown: 1) It reveals real-time association and dissociation between binding partners, 2) It generates quantitative kinetic parameters, and 3) It can detect bindings that pulldown assays often fail to detect. These characteristics have enabled us to deduce the physiological roles of GrgA in gene expression regulation in Chlamydia, and possible detailed interaction mechanisms. We envision that this relatively affordable technology can be extremely useful for studying transcription and other biological processes.

Application of Biolayer Interferometry BLI for Studying Protein-Protein Interactions in Transcription

Interactions of transcription factors (TFs) with the RNA polymerase are usually studied using pulldown assays. We apply a Biolayer Interferometry (BLI) technology to characterize the interaction of GrgA with the chlamydial RNA polymerase. Compared to pulldown assays, BLI detects real-time association and dissociation, offers higher sensitivity, and is highly quantitative.

A transcription factor&#160;(TF) is a protein that regulates gene expression by interacting with the RNA polymerase, another TF, and/or template DNA. GrgA ...

PeptiQuick, a One-Step Incorporation of Membrane Proteins into Biotinylated Peptidiscs for Streamlined Protein Binding Assays

Membrane proteins, including transporters, channels, and receptors, constitute nearly one-fourth of the cellular proteome and over half of current drug targets. Yet, a major barrier to their characterization and exploitation in academic or industrial settings is that most biochemical, biophysical, and drug screening strategies require these proteins to be in a water-soluble state. Our laboratory recently developed the peptidisc, a membrane mimetic offering a &#8220;one-size-fits-all&#8221; approach to the problem of membrane protein solubility. We present here a streamlined protocol that combines protein purification and peptidisc reconstitution in a single chromatographic step. This workflow, termed PeptiQuick, allows for bypassing dialysis and incubation with polystyrene beads, thereby greatly reducing exposure to detergent, protein denaturation, and sample loss. When PeptiQuick is performed with biotinylated scaffolds, the preparation can be directly attached to streptavidin-coated surfaces. There is no need to biotinylate or modify the membrane protein target. PeptiQuick is showcased here with the membrane receptor FhuA and antimicrobial ligand colicin M, using biolayer interferometry to determine the precise kinetics of their interaction. It is concluded that PeptiQuick is a convenient way to prepare and analyze membrane protein-ligand interactions within one&#160;day in a detergent-free environment.

We present a method that combines membrane protein purification and reconstitution into peptidiscs in a single chromatographic step. Biotinylated scaffolds are used for direct surface attachment and measurement of protein-ligand interactions via biolayer interferometry.

Membrane proteins, including transporters, channels, and receptors, constitute nearly one-fourth of the cellular proteome and over half of current drug ...

Creating Highly Specific Chemically Induced Protein Dimerization Systems by Stepwise Phage Selection of a Combinatorial Single-Domain Antibody Library

Protein dimerization events that occur only in the presence of a small-molecule ligand enable the development of small-molecule biosensors for the dissection and manipulation of biological pathways. Currently, only a limited number of chemically induced dimerization (CID) systems exist and engineering new ones with desired sensitivity and selectivity for specific small-molecule ligands remains a challenge in the field of protein engineering. We here describe a high throughput screening method, combinatorial binders-enabled selection of CID (COMBINES-CID), for the de novo engineering of CID systems applicable to a large variety of ligands. This method uses the two-step selection of a phage-displayed combinatorial nanobody library to obtain 1) &#34;anchor binders&#34; that first bind to a ligand of interest and then 2) &#34;dimerization binders&#34; that only bind to anchor binder-ligand complexes. To select anchor binders, a combinatorial library of over 109 complementarity-determining region (CDR)-randomized nanobodies is screened with a biotinylated ligand and hits are validated with the unlabeled ligand by bio-layer interferometry (BLI). To obtain dimerization binders, the nanobody library is screened with anchor binder-ligand complexes as targets for positive screening and the unbound anchor binders for negative screening. COMBINES-CID is broadly applicable to select CID binders with other immunoglobulin, non-immunoglobulin, or computationally designed scaffolds to create biosensors for in vitro and in vivo detection of drugs, metabolites, signaling molecules, etc.

Creating chemically induced protein dimerization systems with desired affinity and specificity for any given small molecule ligand would have many biological sensing and actuation applications. Here, we describe an efficient, generalizable method for de novo engineering of chemically induced dimerization systems via the stepwise selection of a phage-displayed combinatorial single-domain antibody library.

Protein dimerization events that occur only in the presence of a small-molecule ligand enable the development of small-molecule biosensors for the ...

JUMPn: A Streamlined Application for Protein Co-Expression Clustering and Network Analysis in Proteomics

With recent advances in mass spectrometry-based proteomics technologies, deep profiling of hundreds of proteomes has become increasingly feasible. However, deriving biological insights from such valuable datasets is challenging. Here we introduce a systems biology-based software JUMPn, and its associated protocol to organize the proteome into protein co-expression clusters across samples and protein-protein interaction (PPI) networks connected by modules (e.g., protein complexes). Using the R/Shiny platform, the JUMPn software streamlines the analysis of co-expression clustering, pathway enrichment, and PPI module detection, with integrated data visualization and a user-friendly interface. The main steps of the protocol include installation of the JUMPn software, the definition of differentially expressed proteins or the (dys)regulated proteome, determination of meaningful co-expression clusters and PPI modules, and result visualization. While the protocol is demonstrated using an isobaric labeling-based proteome profile, JUMPn is generally applicable to a wide range of quantitative datasets (e.g., label-free proteomics). The JUMPn software and protocol thus provide a powerful tool to facilitate biological interpretation in quantitative proteomics.

We present a systems biology tool JUMPn to perform and visualize network analysis for quantitative proteomics data, with a detailed protocol including data pre-processing, co-expression clustering, pathway enrichment, and protein-protein interaction network analysis.

With recent advances in mass spectrometry-based proteomics technologies, deep profiling of hundreds of proteomes has become increasingly feasible. ...

Exploring Biomolecular Interaction Between the Molecular Chaperone Hsp90 and Its Client Protein Kinase Cdc37 using Field-Effect Biosensing Technology

Biomolecular interactions play versatile roles in numerous cellular processes&#160;by regulating and coordinating functionally relevant biological events. Biomolecules such as proteins, carbohydrates, vitamins, fatty acids, nucleic acids, and enzymes are fundamental building blocks of living beings; they assemble into complex networks in biosystems to synchronize a myriad of life events. Proteins typically utilize complex interactome networks to carry out their functions; hence it is mandatory to evaluate such interactions to unravel their importance in cells at both cellular and organism levels. Toward this goal, we introduce a rapidly emerging technology, field-effect biosensing (FEB), to determine specific biomolecular interactions. FEB is a benchtop, label-free, and reliable biomolecular detection technique to determine specific interactions and uses high-quality electronic-based biosensors. The FEB technology can monitor interactions in the nanomolar range due to the biocompatible nanomaterials used on its biosensor surface. As a proof of concept, the protein-protein interaction (PPI) between heat shock protein 90 (Hsp90) and cell division cycle 37 (Cdc37) was elucidated. Hsp90 is an ATP-dependent molecular chaperone that plays an essential role in the folding, stability, maturation, and quality control of many proteins, thereby regulating multiple vital cellular functions. Cdc37 is regarded as a protein kinase-specific molecular chaperone, as it specifically recognizes and recruits protein kinases to Hsp90 to regulate their downstream signal transduction pathways. As such, Cdc37 is considered a co-chaperone of Hsp90. The chaperone-kinase pathway (Hsp90/Cdc37 complex) is hyper-activated in multiple malignancies promoting cellular growth; therefore, it is a potential target for cancer therapy. The present study demonstrates the efficiency of FEB technology using the Hsp90/Cdc37 model system. FEB detected a strong PPI between the two proteins (KD values of 0.014 &#181;M, 0.053 &#181;M, and 0.072 &#181;M in three independent experiments). In summary, FEB is a label-free and cost-effective PPI detection platform, which offers fast and accurate measurements.

Field-effect biosensing (FEB) is a label-free technique for detecting biomolecular interactions. It measures the electric current through the graphene biosensor to which the binding targets are immobilized. The FEB technology was used to evaluate biomolecular interactions between Hsp90 and Cdc37 and a strong interaction between the two proteins was detected.

Biomolecular interactions play versatile roles in numerous cellular processes&#160;by regulating and coordinating functionally relevant biological events. ...

Pulldown Assay Coupled with Co-Expression in Bacteria Cells as a Time-Efficient Tool for Testing Challenging Protein-Protein Interactions

Pulldown is an easy and widely used protein-protein interaction assay. However, it has limitations in studying protein complexes that do not assemble effectively in vitro. Such complexes may require co-translational assembly and the presence of molecular chaperones; either they form stable oligomers which cannot dissociate and re-associate in vitro or are unstable without a binding partner. To overcome these problems, it is possible to use a method based on the bacterial co-expression of differentially tagged proteins using a set of compatible vectors followed by the conventional pulldown techniques. The workflow is more time-efficient compared to traditional pulldown because it lacks the time-consuming steps of separate purification of interacting proteins and their following incubation. Another advantage is a higher reproducibility due to a significantly smaller number of steps and a shorter period of time in which proteins that exist within the in vitro environment are exposed to proteolysis and oxidation. The method was successfully applied for studying a number of protein-protein interactions when other in vitro techniques were found to be unsuitable. The method can be used for batch testing protein-protein interactions. Representative results are shown for studies of interactions between BTB domain and intrinsically disordered proteins, and of heterodimers of zinc-finger-associated domains.

Here, we describe a method for the bacterial co-expression of differentially tagged proteins using a set of compatible vectors, followed by the conventional pulldown techniques to study protein complexes that cannot assemble in vitro.

Pulldown is an easy and widely used protein-protein interaction assay. However, it has limitations in studying protein complexes that do not assemble ...

A Python-Based Tool for Accurate Mass Calculation of Biotherapeutic Entities

An Open-Source Framework for Mass Calculation of Antibody-Based Therapeutic Molecules

Biotherapeutic masses are a means of verifying identity and structural integrity. Mass spectrometry (MS) of intact proteins or protein subunits provides an easy analytical tool for different stages of biopharmaceutical development. The protein's identity is confirmed when the experimental mass from MS is within a pre-defined mass error range of the theoretical mass. While several computational tools exist for the calculation of protein and peptide molecular weights, they either were not designed for direct application to biotherapeutic entities, have access limitations due to paid licenses, or require uploading protein sequences to host servers. 
We have developed a modular mass calculation routine that enables the easy determination of the average or monoisotopic masses and elemental compositions of therapeutic glycoproteins, including monoclonal antibodies (mAb), bispecific antibodies (bsAb), and antibody-drug conjugates (ADC). The modular nature of this Python-based calculation framework will allow the extension of this platform to other modalities such as vaccines, fusion proteins, and oligonucleotides in the future, and this framework could also be useful for the interrogation of top-down mass spectrometry data. By creating an open-source standalone desktop application with a graphical user interface (GUI), we hope to overcome the restrictions around use in environments where proprietary information cannot be uploaded to web-based tools. This article describes the algorithms and application of this tool, mAbScale, to different antibody-based therapeutic modalities.

Author Spotlight: Advancing Biotherapeutic Mass Calculation by Introducing mAbScale, a Python-Based Desktop Application

This article describes the use of a software application, mAbScale, for the calculation of masses for monoclonal antibody-based protein therapeutics.

Biotherapeutic masses are a means of verifying identity and structural integrity. Mass spectrometry (MS) of intact proteins or protein subunits provides ...