Departamento de Microbiología, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz, Spain.
Fungal Genet Biol. 2010 May;47(5):433-45. doi: 10.1016/j.fgb.2010.02.007. Epub 2010 Mar 3.
We have cloned and characterized the RAD51 and RAD59 orthologs of the pathogenic fungus Candida albicans. CaRad51 exhibited more than 50% identity with several other eukaryotes and the conserved the catalytic domain of a bacterial RecA. As compared to the parental strain, null strains of rad51 exhibited a filamentous morphology, had a decreased grow rate and exhibited a moderate sensitivity to UV light, oxidizing agents, and compounds that cause double-strand breaks (DSB), indicating a role in DNA repair. By comparison, the rad52 null had a higher percentage of filaments, a more severe growth defect and a greater sensitivity to DNA-damaging compounds. Null strains of rad59 showed a UV-sensitive phenotype but behaved similarly to the parental strain in the rest of the assays. As compared to Saccharomyces cerevisiae, C. albicans was much more resistant to bleomycin and the same was true for their respective homologous recombination (HR) mutants. These results indicate that, as described in S. cerevisiae, RAD52 plays a more prominent role than RAD51 in the repair of DSBs in C. albicans and suggest the existence of at least two Rad52-dependent HR pathways, one dependent and one independent of Rad51.
我们已经克隆并鉴定了病原真菌白色念珠菌的 RAD51 和 RAD59 直系同源物。CaRad51 与其他几种真核生物的相似度超过 50%，并保留了细菌 RecA 的催化结构域。与亲本菌株相比，rad51 缺失株表现出丝状形态，生长速度降低，对紫外线、氧化剂和导致双链断裂（DSB）的化合物中度敏感，表明其在 DNA 修复中发挥作用。相比之下，rad52 缺失株的丝状细胞比例更高，生长缺陷更严重，对 DNA 损伤化合物更敏感。rad59 缺失株表现出对紫外线敏感的表型，但在其余的实验中表现与亲本菌株相似。与酿酒酵母相比，白色念珠菌对博来霉素的抗性更强，其同源重组（HR）突变株也是如此。这些结果表明，正如在酿酒酵母中描述的那样，RAD52 在白色念珠菌 DSB 的修复中比 RAD51 发挥更重要的作用，并表明至少存在两种依赖 Rad52 的 HR 途径，一种依赖 Rad51，另一种不依赖 Rad51。
