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 ∼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 2
n
− 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.