Rosenquist T A, Zharkov D O, Grollman A P
Department of Pharmacological Sciences, State University of New York at Stony Brook, Stony Brook, NY 11794-8651, USA.
Proc Natl Acad Sci U S A. 1997 Jul 8;94(14):7429-34. doi: 10.1073/pnas.94.14.7429.
Oxidative DNA damage is generated by reactive oxygen species. The mutagenic base, 8-oxoguanine, formed by this process, is removed from oxidatively damaged DNA by base excision repair. Genes coding for DNA repair enzymes that recognize 8-oxoguanine have been reported in bacteria and yeast. We have identified and characterized mouse and human cDNAs encoding homologs of the 8-oxoguanine DNA glycosylase (ogg1) gene of Saccharomyces cerevisiae. Escherichia coli doubly mutant for mutM and mutY have a mutator phenotype and are deficient in 8-oxoguanine repair. The recombinant mouse gene (mOgg1) suppresses the mutator phenotype of mutY/mutM E. coli. Extracts prepared from mutY/mutM E. coli expressing mOgg1 contain an activity that excises 8-oxoguanine from DNA and a beta-lyase activity that nicks DNA 3' to the lesion. The mouse ogg1 gene product acts efficiently on DNA duplexes in which 7, 8-dihydroxy-8-oxo-2'-deoxyguanosine (8-oxodG) is paired with dC, acts weakly on duplexes in which 8-oxodG is paired with dT or dG, and is inactive against duplexes in which 8-oxodG is paired with dA. Mouse and human ogg1 genes contain a helix-hairpin-helix structural motif with conserved residues characteristic of a recently defined family of DNA glycosylases. Ogg1 mRNA is expressed in several mouse tissues; highest levels were detected in testes. Isolation of the mouse ogg1 gene makes it possible to modulate its expression in mice and to explore the involvement of oxidative DNA damage and associated repair processes in aging and cancer.
氧化性DNA损伤由活性氧产生。此过程形成的诱变碱基8-氧代鸟嘌呤,通过碱基切除修复从氧化损伤的DNA中去除。细菌和酵母中已报道了编码识别8-氧代鸟嘌呤的DNA修复酶的基因。我们已经鉴定并表征了编码酿酒酵母8-氧代鸟嘌呤DNA糖基化酶(ogg1)基因同源物的小鼠和人cDNA。mutM和mutY的大肠杆菌双突变体具有突变表型,并且在8-氧代鸟嘌呤修复方面存在缺陷。重组小鼠基因(mOgg1)可抑制mutY/mutM大肠杆菌的突变表型。从表达mOgg1的mutY/mutM大肠杆菌制备的提取物含有从DNA中切除8-氧代鸟嘌呤的活性以及在损伤位点3'处切割DNA的β-裂解酶活性。小鼠ogg1基因产物对7,8-二羟基-8-氧代-2'-脱氧鸟苷(8-氧代dG)与dC配对的DNA双链体有效作用,对8-氧代dG与dT或dG配对的双链体作用较弱,对8-氧代dG与dA配对的双链体无活性。小鼠和人ogg1基因包含一个螺旋-发夹-螺旋结构基序,具有最近定义的DNA糖基化酶家族的保守残基特征。Ogg1 mRNA在几种小鼠组织中表达;在睾丸中检测到最高水平。小鼠ogg1基因的分离使得调节其在小鼠中的表达以及探索氧化性DNA损伤和相关修复过程在衰老和癌症中的作用成为可能。