Functions required for vitamin B12-dependent ethanolamine utilization in Salmonella typhimurium.
Functions required for vitamin B12-dependent ethanolamine utilization in Salmonella typhimurium.
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鼠伤寒沙门氏菌中维生素 B12 依赖性乙醇胺利用所需的功能。
DOI：
10.1128/jb.171.6.3316-3323.1989
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发表时间：
1989
影响因子：
3.2
通讯作者：
Roth,JR
中科院分区：
文献类型：
--
作者：
Roof,DM;Roth,JR
当B12可用时，鼠伤寒沙门氏菌可以降解乙醇胺以提供碳和氮源。B12是必不可少的，因为它是乙醇胺氨裂解酶的辅因子，乙醇胺分解中的第一种酶。S.鼠伤寒沙门氏菌仅在厌氧条件下产生B12;在氧气存在下，必须提供外源性B12以允许乙醇胺利用。乙醇胺利用所需的基因在eut操纵子中编码。对于互补测试，通过将eut操纵子（侧翼为两个Tn 10元件）转座到现有的F质粒中来构建含有eut基因的F'质粒。互补测试确定了eut操纵子中的六个基因。这些基因中的三个编码已知参与乙醇胺降解的酶：乙醇胺氨裂解酶（eutB和eutC）和乙醛脱氢酶（eutE）。一个基因（eutR）似乎编码诱导eut转录所需的正调控蛋白。剩下的两个基因（eutA）的功能被证明是所需的乙醇胺利用只有当氰基-B12或羟基-B12的前体的腺苷-B12辅因子的乙醇胺氨裂解酶; eutA突变体可以使用乙醇胺作为氮源，只有当腺苷-B12提供。eutD基因没有任何功能，它是使用乙醇胺作为碳源所必需的。eut突变体的乙醇胺摄取试验表明eut操纵子中没有编码乙醇胺通透酶。
When B12 is available, Salmonella typhimurium can degrade ethanolamine to provide a source of carbon and nitrogen. B12 is essential since it is a cofactor for ethanolamine ammonia-lyase, the first enzyme in ethanolamine breakdown. S. typhimurium makes B12 only under anaerobic conditions; in the presence of oxygen, exogenous B12 must be provided to permit ethanolamine utilization. Genes required for ethanolamine utilization are encoded in the eut operon. For complementation testing, an F' plasmid containing the eut genes was constructed by transposition of the eut operon (flanked by two Tn10 elements) to an existing F plasmid. Complementation tests defined six genes in the eut operon. Three of these genes encode enzymes known to be involved in degradation of ethanolamine: ethanolamine ammonia-lyase (eutB and eutC) and acetaldehyde dehydrogenase (eutE). One gene (eutR) seems to encode a positive regulatory protein required for induction of transcription of eut. The function of one of the remaining two genes (eutA) was shown to be required for ethanolamine utilization only when cyano-B12 or hydroxy-B12 were the precursors of the adenosyl-B12 cofactor of ethanolamine ammonia-lyase; eutA mutants could use ethanolamine as the nitrogen source only when adenosyl-B12 was provided. No function has been assigned to the eutD gene, which is required for use of ethanolamine as a carbon source. Ethanolamine uptake assays of eut mutants suggest that no ethanolamine permease is encoded in the eut operon.