8-hydroxyguanine (7,8-dihydro-8-oxoguanine) DNA glycosylase and AP lyase activities of hOGG1 protein and their substrate specificity

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• 作者：Shinmura ; Kazuya ; Kasai ; Hiroshi ; Sasaki ; Atsushi ; Sugimura ; Haruhiko ; Yokota ; Jun
• 关键词：OGG1 ; mutM ; 8-hydroxyguanine ; Base excision repair ; Glycosylase ; Endonuclease ; oh⁸Gua ; 8-hydroxyguanine ; hOGG1 ; human OGG1 ; yOGG1 ; yeast OGG1 ; AP ; apurinic/apyrimidinic ; HPLC ; high performance liquid chromatography ; ECD ; electrochemical detecto
• 刊名：Mutation Research/DNA Repair
• 出版年：1997
• 出版时间：October, 1997
• 年：1997
• 卷：385
• 期：1
• 页码：75-82
• 全文大小：941 K

文摘

Recently we cloned a structural human homolog (hOGG1) of the yeast OGG1 (yOGG1) gene that is involved in the excision repair of 8-hydroxyguanine (also known as 7,8-dihydro-8-oxoguanine; oh⁸Gua). hOGG1 protein shares 38 % amino acid identity with yOGG1 protein. In this paper, we define the substrate specificity of oh⁸Gua DNA glycosylase and AP lyase activities of the hOGG1 protein. The oh⁸Gua released from oh⁸Gua containing DNA was measured by analysis with HPLC coupled with electrochemical detector (ECD) and cleavage sites in the DNA were identified by cleavage assay using gel electrophoresis. GST-hOGG1 protein possessed the oh⁸Gua DNA glycosylase/AP lyase activity and weak δ-elimination activity. oh⁸Gua opposite the C in duplex oligonucleotide was most efficiently released by GST-hOGG1 protein and oh⁸Gua opposite the T was also released, while oh⁸Gua opposite the G or A was very slowly done. The rank order of DNA cleavage efficiency was the same as that of oh⁸Gua glycosylase activity. Glycosylase/AP lyase activities and their substrate specificities of the GST-hOGG1 protein was similar to GST-yOGG1 protein but different from MutM protein. These results indicate that the dominant function of hOGG1 protein is a oh⁸Gua glycosylase reaction by specifically recognizing oh⁸Gua and pyrimidine opposite the oh⁸Gua and δ-elimination reaction in the same manner as yOGG1 protein. Thus, the hOGG1 gene is a functional human homolog of the yOGG1 gene on oh⁸Gua excision repair in spite of the low structural identity at amino acid level between hOGG1 and yOGG1 proteins.