3St. Petersburg Branch of Vavilov Institute of General Genetics, Universitetskaya Naberezhnaya 7/9, 199034 St. Petersburg, Russia; fax: (812) 428-7733; E-mail: email@example.com
* To whom correspondence should be addressed.
Received August 18, 2010; Revision received October 14, 2010
We employed a genetic assay based on illegitimate hybridization of heterothallic Saccharomyces cerevisiae strains (the α-test) to analyze the consequences for genome stability of inactivating translesion synthesis (TLS) DNA polymerases. The α-test is the only assay that measures the frequency of different types of mutational changes (point mutations, recombination, chromosome or chromosome arm loss) and temporary changes in genetic material simultaneously. All these events are manifested as illegitimate hybridization and can be distinguished by genetic analysis of the hybrids and cytoductants. We studied the effect of Polζ, Polη, and Rev1 deficiency on the genome stability in the absence of genotoxic treatment and in UV-irradiated cells. We show that, in spite of the increased percent of accurately repaired primary lesions, chromosome fragility, rearrangements, and loss occur in the absence of Polζ and Polη. Our findings contribute to further refinement of the current models of translesion synthesis and the organization of eukaryotic replication fork.
KEY WORDS: Saccharomyces cerevisiae, translesion synthesis, recombination, chromosome stability