The 3′→5′ exonucleases of both DNA polymerases delta and epsilon participate in correcting errors of DNA replication in Saccharomyces cerevisiae. ![]() Dual roles for DNA sequence identity and the mismatch repair system in the regulation of mitotic crossing-over in yeast. A new protein complex promoting the assembly of Rad51 filaments. Direct imaging of RecA nucleation and growth on single molecules of SSB-coated ssDNA. DNA sequence alignment by microhomology sampling during homologous recombination. Chromosome rearrangements via template switching between diverged repeated sequences. Real-time analysis of double-strand DNA break repair by homologous recombination. Separation-of-function mutations in Saccharomyces cerevisiae MSH2 that confer mismatch repair defects but do not affect nonhomologous-tail removal during recombination. Studamire, B., Price, G., Sugawara, N., Haber, J. Two pathways for removal of nonhomologous DNA ends during double-strand break repair in Saccharomyces cerevisiae. Removal of one nonhomologous DNA end during gene conversion by a RAD1- and MSH2-independent pathway. Removal of nonhomologous DNA ends in double-strand break recombination: the role of the yeast ultraviolet repair gene RAD1. Break-induced replication: what is it and what is it for? Cell Cycle 7, 859–864 (2008)įishman-Lobell, J. Catalysis of homologous DNA pairing by yeast Rad51 and Rad54 proteins. RecA filament sliding on DNA facilitates homology search. The poor homology stringency in the heteroduplex allows strand exchange to incorporate desirable mismatches without sacrificing recognition in vivo. Base triplet stepping by the Rad51/RecA family of recombinases. Catalysis of ATP-dependent homologous DNA pairing and strand exchange by yeast RAD51 protein. Mechanism of homologous recombination from the RecA-ssDNA/dsDNA structures. ![]() Mechanisms and regulation of mitotic recombination in Saccharomyces cerevisiae. DNA sequence alignment during homologous recombination. Nearly all mismatch correction depends on the proofreading activity of DNA polymerase-δ, although the repair proteins Msh2, Mlh1 and Exo1 influence the extent of correction. Mismatch correction of strand invasion heteroduplex DNA is strongly polar, favouring correction close to the DSB end. However, when the DSB end contains a 3′ protruding nonhomologous tail, Msh2 promotes the rejection of mismatched substrates. ![]() When recombination occurs without a protruding nonhomologous 3′ tail, the mismatch repair protein Msh2 does not discourage homeologous recombination. ![]() Thus, completing break-induced replication in vivo overcomes the apparent requirement for at least 6–8 consecutive paired bases that has been inferred from in vitro studies 6, 8. With every sixth base pair mismatched, repair was still more than 5%. With every eighth base pair mismatched, repair was about 14% of that of completely homologous sequences. Here, in Saccharomyces cerevisiae, we analysed Rad51-dependent break-induced replication in which the invading DSB end and its donor template share a 108-base-pair homology region and the donor carries different densities of single-base-pair mismatches. Although budding yeast Rad51 has been extensively characterized in vitro 3, 4, 6, 7, 8, 9, the stringency of its search and sensitivity to mismatched sequences in vivo remain poorly defined. The Rad51 (also known as RecA) family of recombinases executes the critical step in homologous recombination: the search for homologous DNA to serve as a template during the repair of DNA double-strand breaks (DSBs) 1, 2, 3, 4, 5, 6, 7.
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