Kre29p is a novel nuclear protein involved in DNA repair and mitotic fidelity in Candida glabrata

Candida glabrata KRE29 is an ortholog of Saccharomyces cerevisiae KRE29. S. cerevisiae Kre29p has been identified by affinity purification as a subunit of the Smc5-Smc6 complex, which is required for DNA repair and chromosome segregation. However, mutant phenotypes of S. cerevisiae KRE29 have not been well characterized and none of its orthologs' functions has been reported. Here we report phenotypic characteristics of a C. glabrata kre29 deletant. The absence of C. glabrata Kre29p resulted in decreased viability, exhibiting cell cycle arrest between late S-phase and metaphase even under normal growth conditions, and also caused an increase of plasmid loss rate, implying that Kre29p is required for mitotic chromosome transmission fidelity. The deletant showed increased sensitivity to high temperature as well as to DNA damaging agents including UV, gamma ray, 4-nitroquinoline-1-oxide and methyl methanesulfonate, and the phenotypes were restored in the KRE29 reintegrant. Consistent with the Δkre29 phenotypes, a Kre29p-GFP fusion protein was located in the nucleus. Furthermore, Kre29p-GFP became concentrated and formed distinct foci after exposure to 4-nitroquinoline-1-oxide. These results suggest the involvement of C. glabrata Kre29p in DNA repair. To our knowledge, this is the first report addressing a cellular protein involved in DNA repair in C. glabrata.