文章基本信息

标题：Purification and Characterization of a Novel DNA Repair Enzyme from the Extremely Radioresistant Bacterium Rubrobacter radiotolerans
其他标题：Purification and Characterization of a Novel DNA Repair Enzyme from the Extremely Radioresistant Bacterium Rubrobacter radiotolerans
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作者：EZAT ASGARANI ; HIROAKI TERATO ; KENJIRO ASAGOSHI 等
期刊名称：Journal of Radiation Research
印刷版ISSN：0449-3060
电子版ISSN：1349-9157
出版年度：2000
卷号：41
期号：1
页码：19-34
DOI：10.1269/jrr.41.19
摘要：Rubrobacter radiotolerans is an extremely radioresistant bacterium. It exhibits higher resistance than the well-known radioresistant bacterium Deinococcus radiodurans , but the molecular mechanisms responsible for the radioresistance of R. radiotolerans remain unknown. In the present study, we have demonstrated the presence of a novel DNA repair enzyme in R. radiotolerans cells that recognizes radiation-induced DNA damages such as thymine glycol, urea residues, and abasic sites. The enzyme was purified from the crude cell extract by a series of chromatography to an apparent physical homogeneity. The purified enzyme showed a single band with a molecular mass of approximately 40 kDa in SDS-polyacrylamide gel electrophoresis, and was designated as R-endonuclease. R-Endonuclease exhibited repair activity for thymine glycol, urea residues, and abasic sites present in plasmid DNA, but did not act on intact DNA, UV-irradiated DNA and DNA containing reduced abasic sites. The substrate specificity together with the salt and pH optima suggests that R-endonuclease is a functional homolog of endonuclease III of Escherichia coli .
关键词：Radioresistant bacteria; Repair enzyme; Thymine glycol; Enzyme purification; Endonuclease III homologue