Name: inducible t7 rna polymerase-mediated multigene expression system, pmgx
Uploaded: 2017-06-27T13:00:00
Description: Watch this Scientific Journal Video about Inducible T7 RNA Polymerase-mediated Multigene Expression System, pMGX at JoVE.com

This work was supported by the Natural Sciences and Engineering Research Council of Canada.

1. Obtaining Genes of Interest
<ol>
	<li>Design synthetic genes.
	<ol>
		<li>Optimize a gene sequence for E. coli expression.</li>
		<li>Remove any problematic restriction sites from the sequence (AvrII, NdeI, EcoRI, and XbaI).</li>
		<li>Incorporate restriction sites for cloning; a 5&#8242;-NdeI site and a 3&#8242;-EcoRI site are recommended. Other sites can be used, if necessary; refer to the multicloning region of the selected plasmid (Figure S1-S4</str...

<ol>
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Methods. 6 (6), 447-450 (2009).</li><li>Jochimsen, B., 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=Five+phosphonate+operon+gene+products+as+components+of+a+multi-subunit+complex+of+the+carbon-phosphorus+lyase+pathway.">Five phosphonate operon gene products as components of a multi-subunit complex of the carbon-phosphorus lyase pathway.</a> Proc. Natl. Acad. Sci. USA. 108 (28), 11393-11398 (2011).</li><li>Martin, V. J. J., Pitera, D. J., Withers, S. T., Newman, J. D., Keasling, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+a+mevalonate+pathway+in+Escherichia+coli+for+production+of+terpenoids.">Engineering a mevalonate pathway in Escherichia coli for production of terpenoids.</a> Nat. Biotechnol. 21 (7), 796-802 (2003).</li><li>Ajikumar, P. K., 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=Isoprenoid+pathway+optimization+for+Taxol+precursor+overproduction+in+Escherichia+coli.">Isoprenoid pathway optimization for Taxol precursor overproduction in Escherichia coli.</a> Science. 330 (6000), 70-74 (2010).</li><li>Boddy, C. N., Hotta, K., Tse, M. L., Watts, R. E., Khosla, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Precursor-directed+biosynthesis+of+epothilone+in+Escherichia+coli.">Precursor-directed biosynthesis of epothilone in Escherichia coli.</a> J. Am. Chem. Soc. 126 (24), 7436-7437 (2004).</li><li>Lundgren, B. R., Boddy, C. 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Commun. 203 (10), 1326-1335 (2016).</li><li>Romier, C., 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=Co-expression+of+protein+complexes+in+prokaryotic+and+eukaryotic+hosts:+experimental+procedures,+database+tracking+and+case+studies.">Co-expression of protein complexes in prokaryotic and eukaryotic hosts: experimental procedures, database tracking and case studies.</a> Acta Crystallogr. D, Biol. Crystallogr. 62 (Pt 10), 1232-1242 (2006).</li><li>Tolia, N. H., Joshua-Tor, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strategies+for+protein+coexpression+in+Escherichia+coli.">Strategies for protein coexpression in Escherichia coli.</a> Nat. Methods. 3 (1), 55-64 (2006).</li><li>Chanda, P. K., Edris, W. A., Kennedy, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+set+of+ligation-independent+expression+vectors+for+co-expression+of+proteins+in+Escherichia+coli.">A set of ligation-independent expression vectors for co-expression of proteins in Escherichia coli.</a> Protein Expr. Purif. 47 (1), 217-224 (2006).</li><li>Kim, K. -. 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=Two-promoter+vector+is+highly+efficient+for+overproduction+of+protein+complexes.">Two-promoter vector is highly efficient for overproduction of protein complexes.</a> Protein Sci. 13 (6), 1698-1703 (2004).</li><li>Tan, S., Kern, R. C., Selleck, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pST44+polycistronic+expression+system+for+producing+protein+complexes+in+Escherichia+coli.">The pST44 polycistronic expression system for producing protein complexes in Escherichia coli.</a> Protein Expr. Purif. 40 (2), 385-395 (2005).</li><li>Chen, X., Pham, E., Truong, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TEV+protease-facilitated+stoichiometric+delivery+of+multiple+genes+using+a+single+expression+vector.">TEV protease-facilitated stoichiometric delivery of multiple genes using a single expression vector.</a> Protein Sci. 19 (12), 2379-2388 (2010).</li><li>Lorenz, T. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymerase+chain+reaction:+basic+protocol+plus+troubleshooting+and+optimization+strategies.">Polymerase chain reaction: basic protocol plus troubleshooting and optimization strategies.</a> J. Vis. Exp. (63), e3998 (2012).</li><li>Lee, P. Y., Costumbrado, J., Hsu, C. -. Y., Kim, Y. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Agarose+gel+electrophoresis+for+the+separation+of+DNA+fragments.">Agarose gel electrophoresis for the separation of DNA fragments.</a> J. Vis. Exp. (62), (2012).</li><li>Sukumaran, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concentration+determination+of+nucleic+acids+and+proteins+using+the+micro-volume+BioSpec-nano-spectrophotometer.">Concentration determination of nucleic acids and proteins using the micro-volume BioSpec-nano-spectrophotometer.</a> J. Vis. Exp. (48), (2011).</li><li>JoVE Science Education Database. Basic Methods in Cellular and Molecular Biology. Molecular Cloning. J. Vis. Exp Available from: <a target="_blank" href="https://www.jove.com/science-education/5074/molecular-cloning">https://www.jove.com/science-education/5074/molecular-cloning</a> (2016)</li><li>JoVE Science Education Database. Basic Methods in Cellular and Molecular Biology. The Western Blot. J. Vis. Exp Available from: <a target="_blank" href="https://www.jove.com/science-education/5065/the-western-blot">https://www.jove.com/science-education/5065/the-western-blot</a> (2016)</li><li>Laible, M., Boonrod, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Homemade+site+directed+mutagenesis+of+whole+plasmids.">Homemade site directed mutagenesis of whole plasmids.</a> J. Vis. Exp. (27), (2009).</li></ol>

Co-expression of multiple genes is increasingly essential, particularly in characterizing and reconstituting complex, multigene metabolic pathways3,4,5. The pMGX system makes multigene co-expression in E. coli routine6,7,8 and accessible to diverse researchers. In this study, five proteins of interest were shown to be simultane...

Co-expression of multiple proteins is increasingly essential, particularly in synthetic biology applications, where multiple functional modules must be expressed1; in studying protein-protein complexes, where expression and function often require co-expression2,3; and in characterizing and harnessing biosynthetic pathways, where each gene in the pathway must be expressed4,5,6,7,8. A number of systems have been developed for co-expression, particularly in the host organism Escherichia coli, the work horse for laboratory recombinant protein expression9. For example, multiple plasmids with differing selectable markers can be used to express individual proteins using a wealth of different expression vectors10,11. Single plasmid systems for multiple protein expression have used either multiple promoters to control the expression of each gene10,12; synthetic operons, where multiple genes are encoded on a single transcript2,13; or, in some cases, a single gene encoding a polypeptide that is ultimately proteolytically processed, yielding the desired proteins of interest14.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55187/55187fig1.jpg" /> 
Figure 1: pMGX workflow showing the construction of a polycistronic vector. The pMGX system provides a flexible, easy-to-use strategy for the construction of synthetic operons under the control of an inducible T7 promoter. <a href="//cloudflare.jove.com/files/ftp_upload/55187/55187fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
In this manuscript, the use of a highly effective system for the construction of multigene synthetic operons under the control of an inducible T7 RNA polymerase (Figure 1) is described. This system allows many genes to be expressed simultaneously from one plasmid. It is based on a plasmid system, originally called pKH22, that has been used successfully for a number of different applications6,7,8. Here, this plasmid set is expanded to include four related vectors: pMGX-A, an expression vector lacking any C- or N-terminal tags and with the ampicillin resistance marker; pMGX-hisA, an expression vector encoding an N-terminal hexahistidine tag and with the ampicillin resistance marker; pMGX-K, an expression vector lacking any C- or N-terminal tags and with the kanamycin resistance marker; and pMGX-hisK, an expression vector encoding an N-terminal hexahistidine tag and with the kanamycin resistance marker. In this study, the method for generating a polycistronic vector containing five genes using the pMGX system, specifically pMGX-A, is demonstrated along with the successful production of each individual protein in Escherichia coli.

<table border="0" cellpadding="0" cellspacing="0" width="1224">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:327px;">Enzymes</td>
			<td style="width:312px;"></td>
			<td style="width:139px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Alkaline Phosphatase, Calf Intestinal (CIP)</td>
			<td style="width:312px;">New England Biolabs</td>
			<td style="width:139px;">M0290S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">AvrII</td>
			<td style="width:312px;">New England Biolabs</td>
			<td style="width:139px;">R0174S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EcoRI</td>
			<td style="width:312px;">New England Biolabs</td>
			<td style="width:139px;">R0101S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NdeI</td>
			<td style="width:312px;">New England Biolabs</td>
			<td style="width:139px;">R0111S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">XbaI</td>
			<td style="width:312px;">New England Biolabs</td>
			<td style="width:139px;">R0145S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Herculase II Fusion DNA Polymerase</td>
			<td style="width:312px;">Agilent Technologies</td>
			<td style="width:139px;">600677</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">T4 DNA Ligase</td>
			<td style="width:312px;">New England Biolabs</td>
			<td style="width:139px;">M0202S</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:327px;">Name</td>
			<td style="width:312px;">Company</td>
			<td style="width:139px;">Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:327px;">Reagents</td>
			<td style="width:312px;"></td>
			<td style="width:139px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1 kb DNA ladder</td>
			<td style="width:312px;">New England Biolabs</td>
			<td style="width:139px;">N3232L</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4-20% Mini-PROTEAN TGX Stain-Free Protein Gels</td>
			<td style="width:312px;">Bio-Rad</td>
			<td style="width:139px;">456-8095</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">50 x TAE</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">BP1332-4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Agar</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">BP1423-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Agarose</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">BP160-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ampicilin</td>
			<td style="width:312px;">Sigma-Alrich</td>
			<td style="width:139px;">A9518-5G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BL21 (DE3) chemically comeptent cells</td>
			<td></td>
			<td style="width:139px;"></td>
			<td style="width:448px;">Comeptent cell prepared in house</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">B-PER Bacterial Protein Extraction Reagent</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td>PI78243</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">dNTP mix</td>
			<td style="width:312px;">Agilent Technologies</td>
			<td style="width:139px;"></td>
			<td>Supplied with polymerase</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gel Extraction Kit</td>
			<td style="width:312px;">Omega</td>
			<td style="width:139px;">D2500-02</td>
			<td>E.Z.N.A Gel Extraction, supplied by VWR Cat 3: CA101318-972</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glycine</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">BP381-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">His Tag Antibody [HRP], mAb, Mouse</td>
			<td style="width:312px;">GenScript</td>
			<td style="width:139px;">A00612</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Immobilon Western Chemiluminescent HRP Substrate</td>
			<td style="width:312px;">EMD Millipore</td>
			<td style="width:139px;">WBKLS0100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">IPTG</td>
			<td style="width:312px;">Sigma-Alrich</td>
			<td style="width:139px;">15502-10G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LB</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">BP1426-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Methanol</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">A411-20</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pasteurized instant skim milk powder</td>
			<td style="width:312px;">Local grocery store</td>
			<td style="width:139px;"></td>
			<td>No-name grocery store milk is adequate</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Nitrocellulose membrane</td>
			<td style="width:312px;">Amersham Protran (GE Healthcare Life Sciences)</td>
			<td style="width:139px;">10600007</td>
			<td>Membrane PT 0.45 &#181;m 200 mm X 4 m, supplied by VWR Cat #: CA10061-086</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Plasmid DNA Isolation Kit</td>
			<td style="width:312px;">Omega</td>
			<td style="width:139px;">D6943-02</td>
			<td>E.Z.N.A Plasmid DNA MiniKit I, supplied by VWR Cat #: CA101318-898</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">pMGX</td>
			<td style="width:312px;">Boddy Lab</td>
			<td style="width:139px;"></td>
			<td>Request from the Boddy Lab Contact cboddy@uottawa.ca</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Primers</td>
			<td style="width:312px;">Intergrated DNA Technologies</td>
			<td style="width:139px;"></td>
			<td>Design primers as needed for desired gene</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Synthetic Gene</td>
			<td style="width:312px;">Life Technologies</td>
			<td style="width:139px;"></td>
			<td>Design and optimize as needed</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thick Blot Filter Paper</td>
			<td style="width:312px;">Bio-Rad</td>
			<td style="width:139px;">1703932</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tris base</td>
			<td style="width:312px;">BioShop</td>
			<td style="width:139px;">TRS001.1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tween-20</td>
			<td style="width:312px;">Sigma-Alrich</td>
			<td style="width:139px;">P9416-50ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">XL1-Blue chemically competent cells</td>
			<td></td>
			<td style="width:139px;"></td>
			<td style="width:448px;">Comeptent cell prepared in house</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:327px;">Name</td>
			<td style="width:312px;">Company</td>
			<td style="width:139px;">Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:327px;">Equipment</td>
			<td style="width:312px;"></td>
			<td style="width:139px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BioSpectrometer</td>
			<td style="width:312px;">Eppendorf</td>
			<td style="width:139px;">RK-83600-07</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gel box - PAGE</td>
			<td style="width:312px;">Bio-Rad</td>
			<td style="width:139px;">1658005</td>
			<td>Mini-PROTEIN Tetra Vertical Electrophoresis Cell</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gel Imager</td>
			<td style="width:312px;">Alpha Innotech</td>
			<td style="width:139px;"></td>
			<td>AlphaImager EC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Incubator-oven</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">11-690-650D</td>
			<td>Isotemp</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Incubator-shaker</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">SHKE6000-7</td>
			<td>MaxQ 6000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Personna Razors</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">S04615</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Power Pack</td>
			<td style="width:312px;">Bio-Rad</td>
			<td style="width:139px;">S65533Q</td>
			<td>FB300</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Transilluminator</td>
			<td style="width:312px;">VWR International</td>
			<td style="width:139px;">M-10E,6W</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thermocylcer</td>
			<td style="width:312px;">Eppendorf</td>
			<td>Z316091</td>
			<td>Mastercycler Personal, supplied by Sigma</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">UV Face-Shield</td>
			<td style="width:312px;"></td>
			<td style="width:139px;">18-999-4542</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Waterbath</td>
			<td style="width:312px;">Fisher Thermo Scientific</td>
			<td style="width:139px;">15-460-2SQ</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Western Transfer Apparatus</td>
			<td style="width:312px;">Bio-Rad</td>
			<td style="width:139px;">1703935</td>
			<td>Mini-Trans Blot Cell</td>
		</tr>
	</tbody>
</table>

inducible t7 rna polymerase-mediated multigene expression system, pmgx

Co-expression of multiple proteins is increasingly essential for synthetic biology, studying protein-protein complexes, and characterizing and harnessing biosynthetic pathways. In this manuscript, the use of a highly effective system for the construction of multigene synthetic operons under the control of an inducible T7 RNA polymerase is described. This system allows many genes to be expressed simultaneously from one plasmid. Here, a set of four related vectors, pMGX-A, pMGX-hisA, pMGX-K, and pMGX-hisK, with either the ampicillin or kanamycin resistance selectable marker (A and K) and either possessing or lacking an N-terminal hexahistidine tag (his) are disclosed. Detailed protocols for the construction of synthetic operons using this vector system are provided along with the corresponding data, showing that a pMGX-based system containing five genes can be readily constructed and used to produce all five encoded proteins in Escherichia coli. This system and protocol enables researchers to routinely express complex multi-component modules and pathways in E. coli.

In this study, the goal was to co-express five proteins from a single plasmid. The five-codon optimized synthetic gene fragments encoding either N- or C-terminal hexahistidine tags were purchased commercially. The synthetic genes were amplified by PCR and individually cloned into a PCR-blunt vector and sequenced. To generate the polycistronic plasmid, the five genes of interest were first cloned into a suitable pMGX plasmid, pMGX-A. Figure 2 shows PCRBlunt-<e...

Watch this Scientific Journal Video about Inducible T7 RNA Polymerase-mediated Multigene Expression System, pMGX at JoVE.com

Inducible T7 RNA Polymerase-mediated Multigene Expression System, pMGX

This study describes methods for the T7-mediated co-expression of multiple genes from a single plasmid in Escherichia coli using the pMGX plasmid system.

Co-expression of multiple proteins is increasingly essential for synthetic biology, studying protein-protein complexes, and characterizing and harnessing ...

The overall goal of this procedure is to construct multigene synthetic operons under the control of an inducible T7 RNA polymerase for expressing multiple proteins simultaneously. This method can help researchers in synthetic biology and biochemistry, enabling them to build multi-protein pathways or study protein complexes that are dependent on co-expression multiple approaches. The main advantage of this technique is that it allows multiple genes to expressed simultaneously in Escherichia coli from a single plasma.Demonstrating the procedure from my lab, will be Mohamed Hassan, a PhD student and Angela Thompson, a Co-op student. After obtaining and amplifying genes of interest according to the text protocol, prepare digestion reactions for the first gene of interest and the pMGX factor. Using a 40 microliter reaction containing 0.5 to 1.5 micrograms of DNA into the indel enzyme.Incubate the reactions at 37 degree Celsius for one hour. Then add EcoRI and allow the digest to proceed for an additional hour. NdeI is added prior to EcoRI to ensure that it digests effectively.NdeI is sensitive to the length in double-stranded DNA on either side of the restriction site. Adding it first ensures that it cuts the full-length circular plasma. Load the digestion reactions on to a 0.7%agarose gel and electrophores the samples at 100 volts for 55 minutes.Then, with a clean scalpel or razor blade, excise the insert and vector bands and place the excise gel segments into 1.5 milliliter tubes. Use a gel extraction kit according to the text protocol to purify the DNA. Set up a 20 microliter ligation reaction containing 0.15 to 0.5 micrograms of vector DNA and appropriate amount of insert depending on the size of the gene and one microliter of T4 DNA ligase.Under aseptic conditions, thaw on ice 100 microliter aliquots of chemically competent XL1-Blue E.coli cells for five minutes. And then add five microliters of the ligation reactions containing a gene of interest to the cells. Incubate the transformations on ice for 30 minutes.Next, heat shock the cells for 45 seconds in a 42 degree Celsius water bath. Then, place the transformations on ice and then add 200 microliters of cold LB medium. Leave the cells to incubate for two minutes.Incubate the cells at 37 degree Celsius in 220 rotations per minute for one hour and spread 100 microliters onto LB agar plates containing an appropriate selectable marker. To screen colonies for possible transformants, compare the number of colonies on the negative control versus the ligation plates. A colony count ratio of one to two is desired.Select four to eight individual colonies from each ligation reaction to inoculate 4 milliliters of LB with the appropriate antibiotic. Incubate the cultures at 37 degree Celsius and 220 rotations per minute overnight. With the plasmid DNA isolation kit, purify the plasmid DNA according to the text protocol and set up 20 microliter digestion reactions with 150 to 500 nanograms of DNA using one microliter each of NdeI and EcoRI.Incubate the digestion reactions at 37 degrees Celsius for two hours. To insert gene two into the pMGX vector containing gene one, setup a 40-microliter digestion reaction containing 0.5 to 1.5 micrograms of vector DNA containing the first gene of interest and one microliter of AVR2. Incubate the reaction at 37 degrees Celsius for 1.5 hours before adding 1.5 microliters of Calf-intestinal phosphatase.Incubate for an additional 30 minutes. Next, set up a 40 microliter digestion reaction containing 0.5 to 1.5 micrograms of the pMGX vector containing the second gene of interest. Using one microliter of AVR2 and xpol.Incubate the reaction at 37 degree Celsius for two hours. Electrophoris the restriction digests on 0.7 agarose gel. And use a clean scalpel eraser to excise the insert and vector bands as demonstrated earlier.After extracting the plasmid DNA and quantifying the sample according to the text protocol, set up a ligation reaction using a 3:1 insert to vector ratio of gene 2 and pMGX-yfg1. Include a negative control using pMGX-yfg1 only. Transform five microliters of each reaction into XL1-Blue cells as demonstrated earlier.Then compare the colony count on the negative control and ligation plates. If there are a large number of colonies on the negative control plate, review the CIP treatment. Select four to eight individual colonies from the ligation reaction and use each colony to inoculate four microliter of LB plus the appropriate antibiotic.Grow at 37 degrees Celsius and 220 rotations per minute overnight. After isolating and quantifying the plasmid DNA as before, screen for effective insertion of the second gene by setting up a digestion reaction containing 150 to 500 nanograms of DNA and one microliter of EcoRI. Incubate the reactions at 37 degrees Celsius for two hours.EcoRI is recommended for screening purposes but in some cases, EcoRI may generate two or more inserts that are similar in size which are difficult to distinguish on a gel. To ensure success, alternative restriction digest enzyme such as NdeI should be used. Separate the digestion reactions on an agarose gel, looking for a band that corresponds to the size of the inserted gene 2.Clone additional genes into the plasmid according to the text protocol. To generate the polycistronic plasmid, the five genes were first cloned into a suitable plasmid, pMGX A.This figure shows pCR-Blunt-yfg1 and pCR-Blunt-yfg2 in the pMGX A plasmid as well as pMGX A digested with indel and EcoRI. To clone the first two genes into pMGX A, the plasmid was digested with indel and EcoRI.After cloning, pMGX-yfg1 and pMGX-yfg2 where digested with AVR2 and xpol to confirm that successful clones were obtained. This figure shows the pMGXyfg1 vector digested with AVR2 and the pMGX-yfg2 vector digested with AVR2 and xpol to isolate gene of interest two. The resulting insert was cloned pMGX-yfg1 to create the pMGX-yfg1 two vector.As seen here, digestion of pMGX-yfg1 two with EcoRI confirmed the successful cloning of gene interest number two into pMGX-yfg1. This gel image demonstrates the difference between digestive plasmids that either had the insert in the correct orientation or in a reverse orientation. An insert in the reverse orientation would two EcoRI sites in close proximity making the resulting digested 50 base pair fragments undetectable on the gel and the backbone larger.Finally, after generating a five-gene polycistronic expression vector, a western blot of the expressed proteins confirms that all five proteins were expressed from a single vector. Note that the protein produced by yfg5 is the same size as yfg1 and is not separated on the gel. Once mastered, this technique can be completed in three or four days for every gene inserted into pMGX backbone if it is done correctly.While attempting this procedure, it's important to remember to treat and linearize vector with the phosphatase such as Calf-intestinal phosphatase to dephosphorylate the five vector. Following this procedure, further experiments such as in vivo multigene expression can be performed in order to characterize and harness biosynthetic pathways for the production natural products or to study protein-protein complexes. This technique paved the way for researchers in the synthetic biology field to produce complex carbohydrates and genetically engineered E.Coli.After watching this video, you should have a good understanding of how to implement the multigene expressions system in E.coli.

inducible-t7-rna-polymerase-mediated-multigene-expression-system-pmgx

Research

JoVE Journal

Genetics

Mapping RNA-RNA Interactions Globally Using Biotinylated Psoralen

Knowing how RNAs interact with themselves and with others is key to understanding RNA based gene regulation in the cell. While examples of RNA-RNA interactions such as microRNA-mRNA interactions have been shown to regulate gene expression, the full extent to which RNA interactions occur in the cell is still unknown. Previous methods to study RNA interactions have primarily focused on subsets of RNAs that are interacting with a particular protein or RNA species. Here, we detail a method named Sequencing of Psoralen crosslinked, Ligated, and Selected Hybrids (SPLASH) that allows genome-wide capture of RNA interactions in vivo in an unbiased manner. SPLASH utilizes in vivo crosslinking, proximity ligation, and high throughput sequencing to identify intramolecular and intermolecular RNA base-pairing partners globally. SPLASH can be applied to different organisms including bacteria, yeast and human cells, as well as diverse cellular conditions to facilitate the understanding of the dynamics of RNA organization under diverse cellular contexts. The entire experimental SPLASH protocol takes about 5 days to complete and the computational workflow takes about 7 days to complete.

Here, we detail the method of Sequencing of Psoralen crosslinked, Ligated, and Selected Hybrids (SPLASH), which enables genome-wide mapping of intramolecular and intermolecular RNA-RNA interactions in vivo. SPLASH can be applied to study RNA interactomes of organisms including yeast, bacteria and humans.

Knowing how RNAs interact with themselves and with others is key to understanding RNA based gene regulation in the cell. While examples of RNA-RNA ...

Kinetics of Lagging-strand DNA Synthesis In Vitro by the Bacteriophage T7 Replication Proteins

Here we provide protocols for the kinetic examination of lagging-strand DNA synthesis in vitro by the replication proteins of bacteriophage T7. The T7 replisome is one of the simplest replication systems known, composed of only four proteins, which is an attractive feature for biochemical experiments. Special emphasis is placed on the synthesis of ribonucleotide primers by the T7 primase-helicase, which are used by DNA polymerase to initiate DNA synthesis. Because the mechanisms of DNA replication are conserved across evolution, these protocols should be applicable, or useful as a conceptual springboard, to investigators using other model systems. The protocols described here are highly sensitive and an experienced investigator can perform these experiments and obtain data for analysis in about a day. The only specialized piece of equipment required is a rapid-quench flow instrument, but this piece of equipment is relatively common and available from various commercial sources. The major drawbacks of these assays, however, include the use of radioactivity and the relative low throughput.

Kinetics of Lagging-strand DNA Synthesis In Vitro by the Bacteriophage T7 Replication Proteins

We describe sensitive, gel-based discontinuous assays to examine the kinetics of lagging-strand initiation using the replication proteins of bacteriophage T7.

Here we provide protocols for the kinetic examination of lagging-strand DNA synthesis in vitro by the replication proteins of bacteriophage T7. The T7 ...

Controllable Ion Channel Expression through Inducible Transient Transfection

Transfection, the delivery of foreign nucleic acids into a cell, is a powerful tool in protein research. Through this method, ion channels can be investigated through electrophysiological analysis, biochemical characterization, mutational studies, and their effects on cellular processes. Transient transfections offer a simple protocol in which the protein becomes available for analysis within a few hours to days. Although this method presents a relatively straightforward and time efficient protocol, one of the critical components is calibrating the expression of the gene of interest to physiological relevant levels or levels that are suitable for analysis. To this end, many different approaches that offer the ability to control the expression of the gene of interest have emerged. Several stable cell transfection protocols provide a way to permanently introduce a gene of interest into the cellular genome under the regulation of a tetracycline-controlled transcriptional activation. While this technique produces reliable expression levels, each gene of interest requires a few weeks of skilled work including calibration of a killing curve, selection of cell colonies, and overall more resources. Here we present a protocol that uses transient transfection of the Transient Receptor Potential cation channel subfamily V member 1 (TRPV1) gene in an inducible system as an efficient way to express a protein in a controlled manner which is essential in ion channel analysis. We demonstrate that using this technique, we are able to perform calcium imaging, whole cell, and single channel analysis with controlled channel levels required for each type of data collection with a single transfection. Overall, this provides a replicable technique that can be used to study ion channels structure and function.

Studying ion channels through a heterologously expressing system has become a core technique in biomedical research. In this manuscript, we present a time efficient method to achieve tightly controlled ion channel expression by performing transient transfection under the control of an inducible promoter.

Transfection, the delivery of foreign nucleic acids into a cell, is a powerful tool in protein research. Through this method, ion channels can be ...

Constitutive and Inducible Systems for Genetic In Vivo Modification of Mouse Hepatocytes Using Hydrodynamic Tail Vein Injection

In research models of liver cancer, regeneration, inflammation, and fibrosis, flexible systems for in vivo gene expression and silencing are highly useful. Hydrodynamic tail vein injection of transposon-based constructs is an efficient method for genetic manipulation of hepatocytes in adult mice. In addition to constitutive transgene expression, this system can be used for more advanced applications, such as shRNA-mediated gene knock-down, implication of the CRISPR/Cas9 system to induce gene mutations, or inducible systems. Here, the combination of constitutive CreER expression together with inducible expression of a transgene or miR-shRNA of choice is presented as an example of this technique. We cover the multi-step procedure starting from the preparation of sleeping beauty-transposon constructs, to the injection and treatment of mice, and the preparation of liver tissue for analysis by immunostaining. The system presented is a reliable and efficient approach to achieve complex genetic manipulations in hepatocytes. It is specifically useful in combination with Cre/loxP-based mouse strains and can be applied to a variety of models in the research of liver disease.

Constitutive and Inducible Systems for Genetic In Vivo Modification of Mouse Hepatocytes Using Hydrodynamic Tail Vein Injection

Hydrodynamic tail vein injection of transposon-based integration vectors enables stable transfection of murine hepatocytes in vivo. Here, we present a practical protocol for transfection systems that enables the long-term constitutive expression of a single transgene or combined constitutive and doxycycline-inducible expression of a transgene or miR-shRNA in the liver.

In research models of liver cancer, regeneration, inflammation, and fibrosis, flexible systems for in vivo gene expression and silencing are highly ...

Semi-quantitative Detection of RNA-dependent RNA Polymerase Activity of Human Telomerase Reverse Transcriptase Protein

Human telomerase reverse transcriptase (TERT) is the catalytic subunit of telomerase, and it elongates telomere through RNA-dependent DNA polymerase activity. Although TERT is named as a reverse transcriptase, structural and phylogenetic analyses of TERT demonstrate that TERT is a member of right-handed polymerases, and relates to viral RNA-dependent RNA polymerases (RdRPs) as well as viral reverse transcriptase. We firstly identified RdRP activity of human TERT that generates complementary RNA stand to a template non-coding RNA and contributes to RNA silencing in cancer cells. To analyze this non-canonical enzymatic activity, we developed RdRP assay with recombinant TERT in 2009, thereafter established in vitro RdRP assay for endogenous TERT. In this manuscript, we describe the latter method. Briefly, TERT immune complexes are isolated from cells, and incubated with template RNA and rNTPs including radioactive rNTP for RdRP reaction. To eliminate single-stranded RNA, reaction products are treated with RNase I, and the final products are analyzed with polyacrylamide gel electrophoresis. Radiolabeled RdRP products can be detected by autoradiography after overnight exposure.

Human telomerase reverse transcriptase (TERT) synthesizes not only telomeric DNA but also double-stranded RNA through RNA-dependent RNA polymerase activity. Here, we describe a newly established assay to detect RNA-dependent RNA polymerase activity of endogenous TERT.

Human telomerase reverse transcriptase (TERT) is the catalytic subunit of telomerase, and it elongates telomere through RNA-dependent DNA polymerase ...

RNA Pull-down Procedure to Identify RNA Targets of a Long Non-coding RNA

Long non-coding RNA (lncRNA), which are sequences of more than 200 nucleotides without a defined reading frame, belong to the regulatory non-coding RNA&#39;s family. Although their biological functions remain largely unknown, the number of these lncRNAs has steadily increased and it is now estimated that humans may have more than 10,000 such transcripts. Some of these are known to be involved in important regulatory pathways of gene expression which take place at the transcriptional level, but also at different steps of RNA co- and post-transcriptional maturation. In the latter cases, RNAs that are targeted by the lncRNA have to be identified. That&#39;s the reason why it is useful to develop a method enabling the identification of RNAs associated directly or indirectly with a lncRNA of interest.
This protocol, which was inspired by previously published protocols allowing the isolation of a lncRNA together with its associated chromatin sequences, was adapted to permit the isolation of associated RNAs. We determined that two steps are critical for the efficiency of this protocol. The first is the design of specific anti-sense DNA oligonucleotide probes able to hybridize to the lncRNA of interest. To this end, the lncRNA secondary structure was predicted by bioinformatics and anti-sense oligonucleotide probes were designed with a strong affinity for regions that display a low probability of internal base pairing. The second crucial step of the procedure relies on the fixative conditions of the tissue or cultured cells that have to preserve the network between all molecular partners. Coupled with high throughput RNA sequencing, this RNA pull-down protocol can provide the whole RNA interactome of a lncRNA of interest.

This RNA pull-down method allows identifying the RNA targets of a long non-coding RNA (lncRNA). Based on the hybridization of home-made, designed anti-sense DNA oligonucleotide probes specific to this lncRNA in an appropriately fixed tissue or cell line, it efficiently allows the capture of all RNA targets of the lncRNA.

Long non-coding RNA (lncRNA), which are sequences of more than 200 nucleotides without a defined reading frame, belong to the regulatory non-coding ...

Exploring the Root Microbiome: Extracting Bacterial Community Data from the Soil, Rhizosphere, and Root Endosphere

The intimate interaction between plant host and associated microorganisms is crucial in determining plant fitness, and can foster improved tolerance to abiotic stresses and diseases. As the plant microbiome can be highly complex, low-cost, high-throughput methods such as amplicon-based sequencing of the 16S rRNA gene are often preferred for characterizing its microbial composition and diversity. However, the selection of appropriate methodology when conducting such experiments is critical for reducing biases that can make analysis and comparisons between samples and studies difficult. This protocol describes in detail a standardized methodology for the collection and extraction of DNA from soil, rhizosphere, and root samples. Additionally, we highlight a well-established 16S rRNA amplicon sequencing pipeline that allows for the exploration of the composition of bacterial communities in these samples, and can easily be adapted for other marker genes. This pipeline has been validated for a variety of plant species, including sorghum, maize, wheat, strawberry, and agave, and can help overcome issues associated with the contamination from plant organelles.

Here, we describe a protocol to obtain amplicon sequence data of soil, rhizosphere, and root endosphere microbiomes. This information can be used to investigate the composition and diversity of plant-associated microbial communities, and is suitable for the use with a wide range of plant species.

The intimate interaction between plant host and associated microorganisms is crucial in determining plant fitness, and can foster improved tolerance to ...

CRISPR Guide RNA Cloning for Mammalian Systems

The outlined protocol describes streamlined methods for the efficient and cost-effective generation of Cas9-associated guide RNAs. Two alternative strategies for guide RNA (gRNA) cloning are outlined based on the usage of the Type IIS restriction enzyme BsmBI in combination with a set of compatible vectors. Outside of the access to Sanger sequencing services to validate the generated vectors, no special equipment or reagents are required aside from those that are standard to modern molecular biology laboratories. The outlined method is primarily intended for cloning one single gRNA or one paired gRNA-expressing vector at a time. This procedure does not scale well for the generation of libraries containing thousands of gRNAs. For those purposes, alternative sources of oligonucleotide synthesis such as oligo-chip synthesis are recommended. Finally, while this protocol focuses on a set of mammalian vectors, the general strategy is plastic and is applicable to any organism if the appropriate gRNA vector is available.

Here, a simple, efficient, and cost-effective method of sgRNA cloning is outlined.

The outlined protocol describes streamlined methods for the efficient and cost-effective generation of Cas9-associated guide RNAs. Two alternative ...

Maintaining Biological Cultures and Measuring Gene Expression in Aphis nerii: A Non-model System for Plant-insect Interactions

Aphids are excellent experimental models for a variety of biological questions ranging from the evolution of symbioses and the development of polyphenisms to questions surrounding insect's interactions with their host plants. Genomic resources are available for several aphid species, and with advances in the next-generation sequencing, transcriptomic studies are being extended to non-model organisms that lack genomes. Furthermore, aphid cultures can be collected from the field and reared in the laboratory for the use in organismal and molecular experiments to bridge the gap between ecological and genetic studies. Last, many aphids can be maintained in the laboratory on their preferred host plants in perpetual, parthenogenic life cycles allowing for comparisons of asexually reproducing genotypes. Aphis nerii, the milkweed-oleander aphid, provides one such model to study insect interactions with toxic plants using both organismal and molecular experiments. Methods for the generation and maintenance of the plant and aphid cultures in the greenhouse and laboratory, DNA and RNA extractions, microsatellite analysis, de novo transcriptome assembly and annotation, transcriptome differential expression analysis, and qPCR verification of differentially expressed genes are outlined and discussed here.

Maintaining Biological Cultures and Measuring Gene Expression in Aphis nerii: A Non-model System for Plant-insect Interactions

The aphid Aphis nerii colonizes on highly-defended plants in the dogbane family (Apocyanaceae) and provides numerous opportunities to study plant-insect interactions. Here, we present a series of protocols for the maintenance of plant and aphid cultures, and the generation and analysis of molecular and -omic data for A. nerii.

Aphids are excellent experimental models for a variety of biological questions ranging from the evolution of symbioses and the development of polyphenisms ...

Inducible and Reversible Dominant-negative (DN) Protein Inhibition

Dominant-negative (DN) protein inhibition is a powerful method to manipulate protein function and offers several advantages over other genome-based approaches. For example, although chimeric and Cre-LoxP targeting strategies have been widely used, the intrinsic limitations of these strategies (i.e., leaky promoter activity, mosaic Cre expression, etc.) have significantly restricted their application. Moreover, a complete deletion of many endogenous genes is embryonically lethal, making it impossible to study gene function in postnatal life. To address these challenges, we have made significant changes to an early genetic engineering protocol and combined a short (transgenic) version of the Rb1 gene with a lysosomal protease procathepsin B (CB), to generate a DN mouse model of Rb1 (CBRb). Due to the presence of a lysosomal protease, the entire CB-RB1 fusion protein and its interacting complex are routed for proteasome-mediated degradation. Moreover, the presence of a tetracycline inducer (rtTA) element in the transgenic construct enables an inducible and reversible regulation of the RB1 protein. The presence of a ubiquitous ROSA-CAG promoter in the CBRb mouse model makes it a useful tool to carry out transient and reversible Rb1 gene ablation and provide researchers a resource for understanding its activity in virtually any cell type where RB1 is expressed.

Inducible and Reversible Dominant-negative DN Protein Inhibition

Here we present a protocol to develop a dominant-negative inducible system, in which any protein can be conditionally inactivated by reversibly overexpressing a dominant-negative mutant version of it.

Dominant-negative (DN) protein inhibition is a powerful method to manipulate protein function and offers several advantages over other genome-based ...