文章基本信息

标题：Role of the Escherichia coli and Human DNA Glycosylases That Remove 5-Formyluracil from DNA in the Prevention of Mutations
其他标题：Role of the Escherichia coli and Human DNA Glycosylases That Remove 5-Formyluracil from DNA in the Prevention of Mutations
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作者：QIU-MEI ZHANG
期刊名称：Journal of Radiation Research
印刷版ISSN：0449-3060
电子版ISSN：1349-9157
出版年度：2001
卷号：42
期号：1
页码：11-19
DOI：10.1269/jrr.42.11
摘要：Ionizing radiation induces a wide variety of modifications to purine and pyrimidine residues. The exocyclic methyl group of thymine does not escape oxidative damage. Any 5-hydroperoxymethyluracil produced is spontaneously decomposed to form 5-formyluracil (5-foU) and 5-hydroxymethyluracil. The yield of 5-foU by ionizing radiation is roughly the same as that of 8-oxoguanine. 5-foU is a potential mutagenic damage in vitro and in vivo . Mammalian cells have an activity that removes 5-foU from X-irradiated DNA. Furthermore, the Nth, Nei and MutM proteins of E. coli have DNA glycosylase/AP lyase activities that recognize and remove 5-foU in DNA. The mutation frequency of 5-foU-containing plasmid increases when replicated in E. coli nthneimutMalkA . Single mutations in the nth , nei or mutM gene do not affect the mutation frequency. Therefore, these gene products are likely backup enzymes used to repair 5-foU in DNA. Furthermore, the human hNTH1 enzyme, a homologue of E. coli Nth, is found to have similar DNA glycosylase activity to that of the Nth protein.
关键词：Ionizing radiation; Reactive oxygen species; Oxidative base damage; 5-Formyluracil; DNA glycosylase; Mutation