文章基本信息

标题：Efficient removal of uracil from G.U mispairs by the mismatch-specific thymine DNA glycosylase from HeLa cells.
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作者：P Neddermann ; J Jiricny
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：1994
卷号：91
期号：5
页码：1642-1646
DOI：10.1073/pnas.91.5.1642
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The uracil DNA glycosylases (EC 3.2.2.3 ) characterized to date remove uracil from DNA irrespective of whether it is base paired with adenine or mispaired with guanine in double-stranded substrates or whether it is found in single-stranded DNA. We report here the characterization of uracil glycosylase activity that can remove the base solely from a mispair with guanine. It does not recognize uracil either in A.U pairs or in single-stranded substrates. The enzyme, a 55-kDa polypeptide, was previously characterized as a mismatch-specific thymine DNA glycosylase and was thought to be responsible solely for the correction (to G.C) of G.T mispairs that arise as a result of spontaneous hydrolytic deamination of 5-methylcytosine to thymine. Given the broader substrate specificity of the enzyme (in addition to uracil and thymine, the protein can also remove 5-bromouracil from mispairs with guanine), we propose that its biological role in vivo may also include the correction of a subset of G.U mispairs inefficiently removed by the more abundant ubiquitous uracil glycosylases, such as those arising from cytosine deamination in G+C-rich regions of the genome.