Name: dna polymerase activity assay using near-infrared fluorescent labeled dna visualized by acrylamide gel electrophoresis
Uploaded: 2017-10-06T15:00:00
Description: Watch this Scientific Journal Video about DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis at JoVE.com

This work was supported by the Research Corporation for Scientific Advancement (Cottrell College Scholar Award #22548) and by TriLink Biotechnologies (ResearchReward Grant #G139).&#160;

1. Activity Assay
NOTE: There are two typical types of assays that are often run to characterize DNA polymerases using the methods described here. They differ in whether they qualitatively characterize overall synthesis (encompassing many steps of DNA synthesis) or whether they quantitatively focus on individual steps. We describe the necessary steps for each of these below. 
NOTE: Because the assembly of materials are relatively complex, for time sensitive experiments, we recommend that al...

<ol>
	<li>Ong, J. L., Loakes, D., Jaroslawski, S., Too, K., Holliger, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Directed+evolution+of+DNA+polymerase,+RNA+polymerase+and+reverse+transcriptase+activity+in+a+single+polypeptide.">Directed evolution of DNA polymerase, RNA polymerase and reverse transcriptase activity in a single polypeptide.</a> J Mol Biol. 361 (3), 537-550 (2006).</li><li>Chen, T., Romesberg, F. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Directed+polymerase+evolution.">Directed polymerase evolution.</a> FEBS letters. 588 (2), 219-229 (2014).</li><li>Leconte, A. M., 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=Directed+evolution+of+DNA+polymerases+for+next-generation+sequencing.">Directed evolution of DNA polymerases for next-generation sequencing.</a> Angew Chem Int Ed Engl. 49 (34), 5921-5924 (2010).</li><li>Xia, G., 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=Directed+evolution+of+novel+polymerase+activities:+mutation+of+a+DNA+polymerase+into+an+efficient+RNA+polymerase.">Directed evolution of novel polymerase activities: mutation of a DNA polymerase into an efficient RNA polymerase.</a> Proc Natl Acad Sci U S A. 99 (10), 6597-6602 (2002).</li><li>Chen, 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=Evolution+of+thermophilic+DNA+polymerases+for+the+recognition+and+amplification+of+C2'-modified+DNA.">Evolution of thermophilic DNA polymerases for the recognition and amplification of C2'-modified DNA.</a> Nat Chem. 8 (6), 556-562 (2016).</li><li>Thirunavukarasu, D., Chen, T., Liu, Z., Hongdilokkul, N., Romesberg, F. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selection+of+2'-Fluoro-Modified+Aptamers+with+Optimized+Properties.">Selection of 2'-Fluoro-Modified Aptamers with Optimized Properties.</a> J Am Chem Soc. 139 (8), 2892-2895 (2017).</li><li>Taylor, A. 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=Catalysts+from+synthetic+genetic+polymers.">Catalysts from synthetic genetic polymers.</a> Nature. 518 (7539), 427-430 (2015).</li><li>Alves Ferreira-Bravo, I., Cozens, C., Holliger, P., DeStefano, 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=Selection+of+2'-deoxy-2'-fluoroarabinonucleotide+(FANA)+aptamers+that+bind+HIV-1+reverse+transcriptase+with+picomolar+affinity.">Selection of 2'-deoxy-2'-fluoroarabinonucleotide (FANA) aptamers that bind HIV-1 reverse transcriptase with picomolar affinity.</a> Nucleic Acids Res. 43 (20), 9587-9599 (2015).</li><li>Schultz, H. 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=Taq+DNA+Polymerase+Mutants+and+2'-Modified+Sugar+Recognition.">Taq DNA Polymerase Mutants and 2'-Modified Sugar Recognition.</a> Biochemistry. 54 (38), 5999-6008 (2015).</li><li>Rosenblum, S. 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=Design+and+discovery+of+new+combinations+of+mutant+DNA+polymerases+and+modified+DNA+substrates.">Design and discovery of new combinations of mutant DNA polymerases and modified DNA substrates.</a> Chembiochem. 18 (8), 816-823 (2017).</li><li>Creighton, S., Goodman, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gel+kinetic+analysis+of+DNA+polymerase+fidelity+in+the+presence+of+proofreading+using+bacteriophage+T4+DNA+polymerase.">Gel kinetic analysis of DNA polymerase fidelity in the presence of proofreading using bacteriophage T4 DNA polymerase.</a> J Biol Chem. 270 (9), 4759-4774 (1995).</li><li>Joyce, C. M., Benkovic, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+polymerase+fidelity:+kinetics,+structure,+and+checkpoints.">DNA polymerase fidelity: kinetics, structure, and checkpoints.</a> Biochemistry. 43 (45), 14317-14324 (2004).</li><li>Leconte, A. M., 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=Discovery,+characterization,+and+optimization+of+an+unnatural+base+pair+for+expansion+of+the+genetic+alphabet.">Discovery, characterization, and optimization of an unnatural base pair for expansion of the genetic alphabet.</a> J Am Chem Soc. 130 (7), 2336-2343 (2008).</li><li>Sanger, F., Nicklen, S., Coulson, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+sequencing+with+chain-terminating+inhibitors.">DNA sequencing with chain-terminating inhibitors.</a> Proc Natl Acad Sci U S A. 74 (12), 5463-5467 (1977).</li><li>Karger, B. L., Guttman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+Sequencing+by+Capillary+Electrophoresis.">DNA Sequencing by Capillary Electrophoresis.</a> Electrophoresis. 30 (Suppl 1), S196-S202 (2009).</li><li>Lawyer, F. 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=High-level+expression,+purification,+and+enzymatic+characterization+of+full-length+Thermus+aquaticus+DNA+polymerase+and+a+truncated+form+deficient+in+5'+to+3'+exonuclease+activity.">High-level expression, purification, and enzymatic characterization of full-length Thermus aquaticus DNA polymerase and a truncated form deficient in 5' to 3' exonuclease activity.</a> PCR Methods Appl. 2 (4), 275-287 (1993).</li><li>Lawyer, F. 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=Isolation,+characterization,+and+expression+in+Escherichia+coli+of+the+DNA+polymerase+gene+from+Thermus+aquaticus.">Isolation, characterization, and expression in Escherichia coli of the DNA polymerase gene from Thermus aquaticus.</a> J Biol Chem. 264 (11), 6427-6437 (1989).</li><li>Carroll, S. S., Cowart, M., Benkovic, S. 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+mutant+of+DNA+polymerase+I+(Klenow+fragment)+with+reduced+fidelity.">A mutant of DNA polymerase I (Klenow fragment) with reduced fidelity.</a> Biochemistry. 30 (3), 804-813 (1991).</li><li>Shendure, J., Ji, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Next-generation+DNA+sequencing.">Next-generation DNA sequencing.</a> Nat Biotechnol. 26 (10), 1135-1145 (2008).</li><li>Larsen, A. 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=A+general+strategy+for+expanding+polymerase+function+by+droplet+microfluidics.">A general strategy for expanding polymerase function by droplet microfluidics.</a> Nat Commun. 7, 11235 (2016).</li><li>Cozens, 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=Enzymatic+Synthesis+of+Nucleic+Acids+with+Defined+Regioisomeric+2'-5'+Linkages.">Enzymatic Synthesis of Nucleic Acids with Defined Regioisomeric 2'-5' Linkages.</a> Angew Chem Int Ed Engl. 54 (51), 15570-15573 (2015).</li></ol>

Here, we have described an assay to characterize the DNA polymerase-mediated synthesis of M-DNA. By using near-infrared labeled DNA primers, and using denaturing polyacrylamide gel electrophoresis to resolve differently sized oligonucleotides, we can obtain single nucleotide resolution on oligonucleotides, enabling precise measurement of synthesis. These approaches can be used to either measure the overall activity of the enzyme (section 2.1) or to measure the Michaelis-Menten parameters of individual steps (note followi...

DNA polymerases perform accurate and efficient DNA synthesis and are essential to maintaining genome integrity. The ability to synthesize hundreds of nucleotides per second without making errors also makes DNA polymerases essential tools in molecular biology and biotechnology. However, these properties also limit the applications for M-DNA substrates; generally speaking, natural DNA polymerases cannot synthesize many potentially valuable M-DNA substrates, likely due to the high selective pressure against using non-standard substrates in vivo. Many groups have developed directed evolution approaches to generate mutant DNA polymerases capable of M-DNA synthesis1a,2,3,4,5; these efforts have expanded the biotechnological utility of DNA6,7,8.
To evaluate the ability of mutant DNA polymerases to synthesize M-DNA, we9,10, and others11,12,13 typically use in vitro measurements of DNA polymerase activity, which are described in this manuscript. In these experiments, DNA polymerases are co-incubated with a labeled primer/template duplex and nucleoside triphosphate substrates; the products are evaluated by gel electrophoresis. Depending on the specific experimental question, mutant DNA polymerases, modified primers, modified templates, or modified nucleoside triphosphates can be used, enabling the systematic biochemical evaluation of the mutant enzyme activity.
Historically, these assays have relied on a 5&#39; radioactive label to track DNA synthesis; most commonly, 32P and 33P have been used; typically, labeling is achieved using T4 polynucleotide kinase11. However, due to the finite lifetime and relatively high cost of radioactive labels and their safe disposal, our group instead uses a synthetic 5&#39; near-infrared fluorophore labeled DNA. Using a relatively low cost near-infrared gel imager, we have observed similar detection limits to prior studies using radioactive labels (unpublished results). We have successfully reproduced past observations9, and we have not observed any large quantitative difference with previously measured rate constants (unpublished results).
To analyze the size of DNA, and thus, the extent of DNA synthesis, we rely on polyacrylamide gel electrophoresis methods developed originally for Sanger sequencing14 before the advent of capillary electrophoresis15. The distance of separation or mobility can be used as a measurement of molecular weight; large format, vertical polyacrylamide gels can achieve single nucleotide resolution, enabling quantitative observation of DNA oligonucleotides of varying lengths.
Collectively, these experiments are a robust method for polymerase characterization. Due to the time sensitive nature of the reactions, preparation and care is necessary to achieve reproducible results. Further, while the acrylamide gel is a highly effective way to measure DNA synthesis, as well as numerous other DNA modifying reactions, with single nucleotide resolution, it can be technically challenging. The protocol here will hopefully enable users to perform these experiments while avoiding the most common mistakes.

<table>
	<tbody>
		<tr>
			<td>Tris HCl</td>
			<td>Promega</td>
			<td>H5123</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Promega</td>
			<td>H5131</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Fisher Scientific</td>
			<td>BP214-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetylated BSA</td>
			<td>Promega</td>
			<td>PR-R3961</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Sigma</td>
			<td>P4504</td>
			<td></td>
		</tr>
		<tr>
			<td>Dithiothreitol (i.e. DTT)</td>
			<td>Research Products International</td>
			<td>D11000</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid (i.e. EDTA) (0.5M solution)</td>
			<td>Sigma</td>
			<td>03690-100mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma</td>
			<td>G5516</td>
			<td></td>
		</tr>
		<tr>
			<td>Formamide</td>
			<td>Acros</td>
			<td>AC42374-5000</td>
			<td></td>
		</tr>
		<tr>
			<td>Orange G</td>
			<td>Sigma Aldrich</td>
			<td>O3756</td>
			<td></td>
		</tr>
		<tr>
			<td>Bromophenol blue</td>
			<td>Fisher Scientific</td>
			<td>50-701-6973</td>
			<td></td>
		</tr>
		<tr>
			<td>dNTPs</td>
			<td>Fisher Scientific</td>
			<td>FERR0191</td>
			<td></td>
		</tr>
		<tr>
			<td>M-dNTPs (riboNTPs)</td>
			<td>Fisher Scientific</td>
			<td>45-001-341 (343, 345, 347)</td>
			<td></td>
		</tr>
		<tr>
			<td>M-dNTPs (all other modified NTPs)</td>
			<td>TriLink Biotechnologies</td>
			<td>assorted</td>
			<td></td>
		</tr>
		<tr>
			<td>primer 1</td>
			<td>IDT DNA / TriLink Biotechnologies</td>
			<td>Custom Syntheses</td>
			<td>We use the IR700 dye which can be purchased as a custom synthesis. We typically purchase the oligonucleotides HPLC purified. Sequence is 5&#8217;-dTAATACGACTCACTATAGGGAGA</td>
		</tr>
		<tr>
			<td>template 1</td>
			<td>IDT DNA / TriLink Biotechnologies</td>
			<td>Custom Syntheses</td>
			<td>We typically purchase the oligonucleotides HPLC purified. Sequence is 5&#8217;-dCGCTAGGACGGCATTGGATCAGTCTCCCTATAGTGAGTCGTATTA</td>
		</tr>
		<tr>
			<td>Acrylamide</td>
			<td>Research Products International</td>
			<td>A11405</td>
			<td>38.67% acrylamide and 1.33% bis-acrylamide</td>
		</tr>
		<tr>
			<td>Tris/Borate/EDTA (TBE) solid</td>
			<td>Research Products International</td>
			<td>T22020</td>
			<td></td>
		</tr>
		<tr>
			<td>Urea ultrapure</td>
			<td>Research Products International</td>
			<td>U20200</td>
			<td></td>
		</tr>
		<tr>
			<td>Gel tape</td>
			<td>CBS Scientific</td>
			<td>GT-72-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Large white spring clamp polypropylene</td>
			<td>CBS Scientific</td>
			<td>GPC-0001</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium persulfate (APS)</td>
			<td>Fisher Scientific</td>
			<td>BP179</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetramethylethylenediamine (TEMED)</td>
			<td>Fisher Scientific</td>
			<td>BP15020</td>
			<td></td>
		</tr>
		<tr>
			<td>0.75 mm spacers</td>
			<td>CBS Scientific</td>
			<td>SGS-20-0740A</td>
			<td></td>
		</tr>
		<tr>
			<td>33x42 Notched Glass Plate Set</td>
			<td>CBS Scientific</td>
			<td>SGP33-040A</td>
			<td></td>
		</tr>
		<tr>
			<td>Wedge plate separator</td>
			<td>CBS Scientific</td>
			<td>WPS-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Comb for gel electrophoresis</td>
			<td>CBS Scientific</td>
			<td>SG33-0734</td>
			<td></td>
		</tr>
		<tr>
			<td>Gel electrophoresis rig</td>
			<td>CBS Scientific</td>
			<td>SG-400-33</td>
			<td></td>
		</tr>
		<tr>
			<td>ultrapure water</td>
			<td></td>
			<td></td>
			<td>we use a Milli-Q system from Millipore</td>
		</tr>
		<tr>
			<td>DNA polymerases</td>
			<td></td>
			<td></td>
			<td>we prepare these in our laboratory using published protocols.</td>
		</tr>
	</tbody>
</table>

dna polymerase activity assay using near-infrared fluorescent labeled dna visualized by acrylamide gel electrophoresis

For any enzyme, robust, quantitative methods are required for characterization of both native and engineered enzymes. For DNA polymerases, DNA synthesis can be characterized using an in vitro DNA synthesis assay followed by polyacrylamide gel electrophoresis. The goal of this assay is to quantify synthesis of both natural DNA and modified DNA (M-DNA). These approaches are particularly useful for resolving oligonucleotides with single nucleotide resolution, enabling observation of individual steps during enzymatic oligonucleotide synthesis. These methods have been applied to the evaluation of an array of biochemical and biophysical properties such as the measurement of steady-state rate constants of individual steps of DNA synthesis, the error rate of DNA synthesis, and DNA binding affinity. By using modified components including, but not limited to, modified nucleoside triphosphates (NTP), M-DNA, and/or mutant DNA polymerases, the relative utility of substrate-DNA polymerase pairs can be effectively evaluated. Here, we detail the assay itself, including the changes that must be made to accommodate nontraditional primer DNA labeling strategies such as near-infrared fluorescently labeled DNA. Additionally, we have detailed crucial technical steps for acrylamide gel pouring and running, which can often be technically challenging.

A successful polyacrylamide gel analysis of a qualitative characterization of overall activity (described in section 2.1, Figure 1) and of steady-state kinetics (described in the note at conclusion of section 2.1, Figure 2) are shown. An unsuccessful polyacrylamide gel analysis is also shown (Figure 3).
Note that no commercially available l...

Watch this Scientific Journal Video about DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis at JoVE.com

DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis

This protocol describes the characterization of DNA polymerase synthesis of modified DNA through observation of changes to near-infrared fluorescently labeled DNA using gel electrophoresis and gel imaging. Acrylamide gels are used for high resolution imaging of the separation of short nucleic acids, which migrate at different rates depending on size.

For any enzyme, robust, quantitative methods are required for characterization of both native and engineered enzymes. For DNA polymerases, DNA synthesis ...

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