Mechanisms of Rad52-independent spontaneous and UV-induced mitotic recombination in Saccharomyces cerevisiae.
In wild-type diploid cells, heteroallelic recombination between his4A and his4C alleles leads mostly to His+ gene conversions that have a parental configuration of flanking markers, but approximately 22% of recombinants have associated reciprocal crossovers. In rad52 strains, gene conversion is reduced 75-fold and the majority of His+ recombinants are crossover associated, with the largest class being half-crossovers in which the other participating chromatid is lost. We report that UV irradiating rad52 cells results in an increase in overall recombination frequency, comparable to increases induced in wild-type (WT) cells, and surprisingly results in a pattern of recombination products quite similar to RAD52 cells: gene conversion without exchange is favored, and the number of 2n - 1 events is markedly reduced. Both spontaneous and UV-induced RAD52-independent recombination depends strongly on Rad50, whereas rad50 has no effect in cells restored to RAD52. The high level of noncrossover gene conversion outcomes in UV-induced rad52 cells depends on Rad51, but not on Rad59. Those outcomes also rely on the UV-inducible kinase Dun1 and Dun1's target, the repressor Crt1, whereas gene conversion events arising spontaneously depend on Rad59 and Crt1. Thus, there are at least two Rad52-independent recombination pathways in budding yeast.
Coïc
Eric
E
Department of Biology and Rosenstiel Center, Brandeis University, Waltham, MA 02454-9110, USA.
Feldman
Taya
T
Landman
Allison S
AS
Haber
James E
JE
D008938:Mitosis / Q000502:physiology*; D051721:Rad52 DNA Repair and Recombination Protein / Q000378:metabolism*; D011995:Recombination, Genetic / Q000235:genetics / Q000528:radiation effects*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D014466:Ultraviolet Rays
C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins