In vitro monitoring of base excision repair in Saccharomyces cerevisiae.

Base excision repair (BER) is an important mechanism to maintain genomic stability. Here we offer a set of protocols to quantitatively analyze BER capacity in whole cell-free yeast extracts. Cell-free yeast extracts were obtained by a French press procedure and repair capacities were measured by using oligonucleotide substrates.

A novel function for the Mre11-Rad50-Xrs2 complex in base excision repair.

The Mre11/Rad50/Xrs2 (MRX) complex in Saccharomyces cerevisiae has well-characterized functions in DNA double-strand break processing, checkpoint activation, telomere length maintenance and meiosis. In this study, we demonstrate an involvement of the complex in the base excision repair (BER) pathway. We studied the repair of methyl-methanesulfonate-induced heat-labile sites in chromosomal DNA in vivo and the in vitro BER capacity for the repair of uracil- and 8-oxoG-containing oligonucleotides in MRX-deficient cells.

Regulation of double-stranded DNA gap repair by the RAD6 pathway.

The RAD6 pathway allows replication across DNA lesions by either an error-prone or error-free mode. Error-prone replication involves translesion polymerases and requires monoubiquitylation at lysine (K) 164 of PCNA by the Rad6 and Rad18 enzymes. By contrast, the error-free bypass is triggered by modification of PCNA by K63-linked polyubiquitin chains, a reaction that requires in addition to Rad6 and Rad18 the enzymes Rad5 and Ubc13-Mms2.