期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 276, 期 2, 页码 884-894出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M008300200
关键词
-
Pyrimidine-requiring cdd mutants of Escherichia coli deficient in cytidine deaminase utilize cytidine as a pyrimidine source by an alternative pathway. This has been presumed to involve phosphorylation of cytidine to CMP by cytidine/uridine kinase and subsequent hydrolysis of CMP to cytosine and ribose 8-phosphate by a putative CMP hydrolase, Here we show that cytidine, in cdd strains, is converted directly to cytosine and ribose by a ribonucleoside hydrolase encoded by the previously uncharacterized gene ybeK, which we have renamed rihA, The RihA enzyme is homologous to the products of two unlinked genes, yeiK and yaaF, which have been renamed rihB and rihC, respectively, The RihB enzyme was shown to be a pyrimidine-specific ribonucleoside hydrolase like RihA, whereas RihC hydrolyzed both pyrimidine and purine ribonucleosides, The physiological function of the ribonucleoside hydrolases in wild-type E, coli strains is enigmatic, as their activities are paralleled by the phosphorolytic activities of the nucleoside phosphorylases, and a triple mutant lacking all three hydrolytic activities grew normally. Furthermore, enzyme assays and lacZ gene fusion analysis indicated that rihB was essentially silent unless activated by mutation, whereas rihA and rihC were poorly expressed in glucose medium due to catabolite repression.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据