冰岛硫化叶菌xpb基因缺失突变体的构建及遗传学分析

为在体内研究古菌核苷酸切除修复(nucleotide excision repair,NER)机制,利用基因敲除的方法,对泉古菌核苷酸切除修复机制进行研究,构建了冰岛硫化叶菌编码真核生物NER解旋酶XPB同源蛋白的基因xpb1和xpb2单缺失突变体,从而在体内分析xpb1和xpb2基因的功能。结果表明:基因xpb1或xpb2不是冰岛硫化叶菌存活的必需基因。表型分析发现,xpb1和xpb2基因单缺失突变体相较野生型菌株REY15A,对DNA损伤试剂4-NQO 4-硝基喹啉-1-氧化物(4-nitroquinoline 1-oxide,4-NQO)分别表现出轻微敏感性和不敏感性,暗示NER解旋酶功能在冰岛硫化叶菌体内存在多重冗余。

Construction of deletion mutants and genetic analysis of xpbs genes in Sul f olobus islandicus

Genome analyses suggested that archaea could possess a eukaryotic-type nucleotide excision repair(NER) pathway because they encode homologs of several eukaryotic NER proteins.To investigate the archaeal nucleotide excision repair pathway in vivo,the genes encoding the potential NER helicases in the genome of the hyperthermophilic crenarchaeon Sulfolobus islandicus were deleted via a gene knock-out strategy and deletion mutants of the xpb1 and xpb2 genes were isolated,indicating that they were not essential to the survival of S.islandicus.Phenotypic analysis of deletion mutants showed that the xpb1 mutant was only slightly sensitive to 4-NQO,as compared with the wild-type strain REY15A,while the xpb2 mutant showed no sensitivity to 4-NQO.It is the first genetic study of the crenarchaeon NER pathway.