Chen X J, Clark-Walker G D
Molecular and Population Genetics Group, Research School of Biological Sciences, Australian National University, Canberra.
Mol Cell Biol. 1994 Jul;14(7):4501-8. doi: 10.1128/mcb.14.7.4501-4508.1994.
A Kluyveromyces lactis mutant, hypersensitive to the DNA-targeting drugs ethidium bromide (EtBr), berenil, and HOE15030, can be complemented by a wild-type gene with homology to SIR2 of Saccharomyces cerevisiae (ScSIR2). The deduced amino acid sequence of the K. lactis Sir2 protein has 53% identity with ScSir2 protein but is 108 residues longer. K. lactis sir2 mutants show decreased mating efficiency, deficiency in sporulation, an increase in recombination at the ribosomal DNA locus, and EtBr-induced death. Some functional equivalence between the Sir2 proteins of K. lactis and S. cerevisiae has been demonstrated by introduction of ScSIR2 into a sir2 mutant of K. lactis. Expression of ScSIR2 on a multicopy plasmid restores resistance to EtBr and complements sporulation deficiency. Similarly, mating efficiency of a sir2 mutant of S. cerevisiae is partially restored by K. lactis SIR2 on a multicopy plasmid. Although these observations suggest that there has been some conservation of Sir2 protein function, a striking difference is that sir2 mutants of S. cerevisiae, unlike their K. lactis counterparts, are not hypersensitive to DNA-targeting drugs.
乳酸克鲁维酵母（Kluyveromyces lactis）的一个对靶向DNA的药物溴化乙锭（EtBr）、贝尼尔和HOE15030高度敏感的突变体，可被与酿酒酵母（Saccharomyces cerevisiae）的SIR2具有同源性的野生型基因所互补。乳酸克鲁维酵母Sir2蛋白的推导氨基酸序列与酿酒酵母ScSir2蛋白有53%的同一性，但长108个残基。乳酸克鲁维酵母sir2突变体表现出交配效率降低、孢子形成缺陷、核糖体DNA位点的重组增加以及EtBr诱导的死亡。通过将ScSIR2导入乳酸克鲁维酵母的sir2突变体，已证明乳酸克鲁维酵母和酿酒酵母的Sir2蛋白之间存在一些功能等效性。多拷贝质粒上ScSIR2的表达恢复了对EtBr的抗性并弥补了孢子形成缺陷。同样，多拷贝质粒上的乳酸克鲁维酵母SIR2部分恢复了酿酒酵母sir2突变体的交配效率。尽管这些观察结果表明Sir2蛋白功能存在一些保守性，但一个显著的差异是，酿酒酵母的sir2突变体与其乳酸克鲁维酵母对应物不同，对靶向DNA的药物不高度敏感。
