Multiple Pathways Promote Short-Sequence Recombination in Saccharomyces cerevisiae

Abstract

ABSTRACT In the budding yeast Saccharomyces cerevisiae , null alleles of several DNA repair and recombination genes confer defects in recombination that grow more severe with decreasing sequence length, indicating that they are required for short-sequence recombination (SSR). RAD1 and RAD10 , which encode the subunits of the structure-specific endonuclease Rad1/10, are critical for SSR. MRE11 , RAD50 , and XRS2 , which encode the subunits of M/R/X, another complex with nuclease activity, are also crucially important. Genetic evidence suggests that Rad1/10 and M/R/X act on the same class of substrates during SSR. MSH2 and MSH3 , which encode subunits of Msh2/3, a complex active during mismatch repair and recombination, are also important for SSR but play a more restricted role. Additional evidence suggests that SSR is distinct from nonhomologous end joining and is superimposed upon basal homologous recombination.