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Two distinct mechanisms of Topoisomerase 1-dependent mutagenesis in yeast.

ABSTRACT: Topoisomerase 1 (Top1) resolves transcription-associated supercoils by generating transient single-strand breaks in DNA. Top1 activity in yeast is a major source of transcription-associated mutagenesis, generating a distinctive mutation signature characterized by deletions in short, tandem repeats. A similar signature is associated with the persistence of ribonucleoside monophosphates (rNMPs) in DNA, and it also depends on Top1 activity. There is only partial overlap, however, between Top1-dependent deletion hotspots identified in highly transcribed DNA and those associated with rNMPs, suggesting the existence of both rNMP-dependent and rNMP-independent events. Here, we present genetic studies confirming that there are two distinct types of hotspots. Data suggest a novel model in which rNMP-dependent hotspots are generated by sequential Top1 reactions and are consistent with rNMP-independent hotspots reflecting processing of a trapped Top1 cleavage complex.

SUBMITTER: Cho JE

PROVIDER: S-EPMC3594648 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature

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Two distinct mechanisms of Topoisomerase 1-dependent mutagenesis in yeast.

Cho Jang-Eun JE Kim Nayun N Li Yue C YC Jinks-Robertson Sue S

DNA repair 20130108 3

Topoisomerase 1 (Top1) resolves transcription-associated supercoils by generating transient single-strand breaks in DNA. Top1 activity in yeast is a major source of transcription-associated mutagenesis, generating a distinctive mutation signature characterized by deletions in short, tandem repeats. A similar signature is associated with the persistence of ribonucleoside monophosphates (rNMPs) in DNA, and it also depends on Top1 activity. There is only partial overlap, however, between Top1-depen ...[more]

PMID: 23305949

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