Mechanisms of Rad52-independent spontaneous and UV-induced mitotic recombination in Saccharomyces cerevisiae

Genetics. 2008 May;179(1):199-211. doi: 10.1534/genetics.108.087189. Epub 2008 May 5.

Abstract

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.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Mitosis / physiology*
  • Rad52 DNA Repair and Recombination Protein / metabolism*
  • Recombination, Genetic / genetics
  • Recombination, Genetic / radiation effects*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Ultraviolet Rays*

Substances

  • RAD52 protein, S cerevisiae
  • Rad52 DNA Repair and Recombination Protein
  • Saccharomyces cerevisiae Proteins