Inaccurate DNA synthesis in cell extracts of yeast producing active human DNA polymerase iota

Mammalian Pol ι has an unusual combination of properties: it is stimulated by Mn(2+) ions, can bypass some DNA lesions and misincorporates "G" opposite template "T" more frequently than incorporates the correct "A." We recently proposed a method of detection of Pol ι ac...

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Published in:PloS one Vol. 6; no. 1; p. e16612
Main Authors: Makarova, Alena V, Grabow, Corinn, Gening, Leonid V, Tarantul, Vyacheslav Z, Tahirov, Tahir H, Bessho, Tadayoshi, Pavlov, Youri I
Format: Journal Article
Language:English
Published: United States Public Library of Science 31-01-2011
Public Library of Science (PLoS)
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Summary:Mammalian Pol ι has an unusual combination of properties: it is stimulated by Mn(2+) ions, can bypass some DNA lesions and misincorporates "G" opposite template "T" more frequently than incorporates the correct "A." We recently proposed a method of detection of Pol ι activity in animal cell extracts, based on primer extension opposite the template T with a high concentration of only two nucleotides, dGTP and dATP (incorporation of "G" versus "A" method of Gening, abbreviated as "misGvA"). We provide unambiguous proof of the "misGvA" approach concept and extend the applicability of the method for the studies of variants of Pol ι in the yeast model system with different cation cofactors. We produced human Pol ι in baker's yeast, which do not have a POLI ortholog. The "misGvA" activity is absent in cell extracts containing an empty vector, or producing catalytically dead Pol ι, or Pol ι lacking exon 2, but is robust in the strain producing wild-type Pol ι or its catalytic core, or protein with the active center L62I mutant. The signature pattern of primer extension products resulting from inaccurate DNA synthesis by extracts of cells producing either Pol ι or human Pol η is different. The DNA sequence of the template is critical for the detection of the infidelity of DNA synthesis attributed to DNA Pol ι. The primer/template and composition of the exogenous DNA precursor pool can be adapted to monitor replication fidelity in cell extracts expressing various error-prone Pols or mutator variants of accurate Pols. Finally, we demonstrate that the mutation rates in yeast strains producing human DNA Pols ι and η are not elevated over the control strain, despite highly inaccurate DNA synthesis by their extracts.
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Conceived and designed the experiments: AVM YIP. Performed the experiments: AVM CG YIP. Analyzed the data: AVM CG LVG VZT TB YIP. Contributed reagents/materials/analysis tools: AVM CG THT YIP. Wrote the paper: AVM LVG VZT THT TB YIP. Analysed protein structures and prepared Fig. 1B: THT.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0016612