Ribar Balazs, Izumi Tadahide, Mitra Sankar
Sealy Center for Molecular Science, University of Texas Medical Branch, 6.148 Medical Research Building, Galveston, TX 77555, USA.
Nucleic Acids Res. 2004 Jan 2;32(1):115-26. doi: 10.1093/nar/gkh151. Print 2004.
The abasic (AP) sites, the major mutagenic and cytotoxic genomic lesions, induced directly by oxidative stress and indirectly after excision of damaged bases by DNA glycosylases, are repaired by AP-endonucleases (APEs). Among two APEs in Saccharomyces cerevisiae, Apn1 provides the major APE activity, and Apn2, the ortholog of the mammalian APE, provides back-up activity. We have cloned apn1 and apn2 genes of Schizosaccharomyces pombe, and have shown that inactivation of Apn2 and not Apn1 sensitizes this fission yeast to alkylation and oxidative damage-inducing agents, which is further enhanced by Apn1 inactivation. We also show that Uve1, present in S.pombe but not in S.cerevisiae, provides the back-up APE activity together with Apn1. We confirmed the presence of APE activity in recombinant Apn2 and in crude cell extracts. Thus S.pombe is distinct from S.cerevisiae, and is similar to mammalian cells in having Apn2 as the major APE.
无碱基（AP）位点是主要的诱变和细胞毒性基因组损伤，可由氧化应激直接诱导产生，也可在DNA糖基化酶切除受损碱基后间接产生，由AP核酸内切酶（APE）修复。在酿酒酵母的两种APE中，Apn1提供主要的APE活性，而哺乳动物APE的直系同源物Apn2提供备用活性。我们克隆了粟酒裂殖酵母的apn1和apn2基因，并表明Apn2而非Apn1的失活使这种裂殖酵母对烷基化和氧化损伤诱导剂敏感，Apn1失活会进一步增强这种敏感性。我们还表明，存在于粟酒裂殖酵母而非酿酒酵母中的Uve1与Apn1一起提供备用APE活性。我们证实了重组Apn2和粗细胞提取物中存在APE活性。因此，粟酒裂殖酵母与酿酒酵母不同，在以Apn2作为主要APE方面与哺乳动物细胞相似。
