We have investigated the 3′-5′-exonuclease activity of phage T7 DNA polymerase for its usefulness as an approach for the detection of lesions in DNA. Unlike the T4 DNA polymerase-exonuclease, which is commonly used to map the position and frequency of lesions in very small DNA fragments, T7 DNA polymerase-exonuclease is able to hydrolyse almost completely the large fragments from KpnI-restricted mammalian DNA. However, we found that the exonuclease was also able to hydrolyse DNA containing several kinds of lesions: cyclobutane pyrimidine dimers, thymine glycols, and mono-adducts of 4′-hydroxymethyl-4,5′,8-trimethylpsoralen and 5′-methyl-isopsoralen. Modifications of the reaction conditions did not significantly alter the extent of hydrolysis. These properties distinguish the T7 DNA polymerase-exonuclease from the T4 DNA polymerase-exonuclease and make the T7 DNA polymerase-exonuclease unsuitable for detecting several types of lesions in DNA.
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Research Article|
July 15 1993
Digestion of damaged DNA by the T7 DNA polymerase-exonuclease
D R Koehler;
D R Koehler
1Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, U.S.A.
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P C Hanawalt
P C Hanawalt
1Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, U.S.A.
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Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1993 The Biochemical Society, London
1993
Biochem J (1993) 293 (2): 451–453.
Citation
D R Koehler, P C Hanawalt; Digestion of damaged DNA by the T7 DNA polymerase-exonuclease. Biochem J 15 July 1993; 293 (2): 451–453. doi: https://doi.org/10.1042/bj2930451
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