期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：20
页码：9127-9131
DOI：10.1073/pnas.88.20.9127
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We described previously the isolation of a Saccharomyces cerevisiae 3-methyladenine (3-MeAde) DNA glycosylase repair gene (MAG) by its expression in glycosylase-deficient Escherichia coli alkA tag mutant cells and its ability to rescue these cells from the toxic effects of alkylating agents. Here we extend this cross-species functional complementation approach to the isolation of a full-length human 3-MeAde DNA glycosylase cDNA that rescues alkA tag E. coli from killing by methyl methanesulfonate, and we have mapped the gene to human chromosome 16. The cloned cDNA, expressed from the pBR322 beta-lactamase promoter, contains an 894-base-pair open reading frame encoding a 32,894-Da protein able to release 3-MeAde, but not 7-methylguanine, from alkylated DNA. Surprisingly, the predicted human protein does not share significant amino acid sequence homology with the bacterial AlkA and Tag glycosylases or the yeast MAG glycosylase, but it does share extensive amino acid sequence homology with a rat 3-MeAde DNA glycosylase and significant DNA sequence homology with genes from several mammalian species. The cloning of a human 3-MeAde DNA glycosylase cDNA represents a key step in generating 3-MeAde repair-deficient cells and the determination of the in vivo role of this DNA repair enzyme in protecting against the toxic and carcinogenic effects of alkylating agents.
