A new pathway for salvaging the coenzyme B12 precursor cobinamide in archaea requires cobinamide-phosphate synthase (CbiB) enzyme activity.
A new pathway for salvaging the coenzyme B12 precursor cobinamide in archaea requires cobinamide-phosphate synthase (CbiB) enzyme activity.
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在古细菌中挽救辅酶 B12 前体钴酰胺的新途径需要钴酰胺磷酸合酶 (CbiB) 的活性。
DOI：
10.1128/jb.185.24.7193-7201.2003
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发表时间：
2003
影响因子：
3.2
通讯作者：
Escalante-Semerena,JorgeC
中科院分区：
文献类型：
--
作者：
Woodson,JesseD;Zayas,CarmenL;Escalante-Semerena,JorgeC
由于古细菌基因组缺乏细菌核苷三磷酸：5 ' -脱氧cobinamide激酶（cobUinSalmonella enterica）的同源物，古细菌抢救cobinamide的能力一直受到质疑。后一种活性是需要在细菌中回收的。本文报道了古细菌利用不同于细菌的途径从环境中回收cobinamide的证据。这些研究需要对两个基因进行功能表征，而这两个基因的推测功能仅仅是基于它们与编码s的腺苷酸和腺苷二酰磷酸合成酶（分别为chbipandchbib）的细菌基因的同源性。血清。古盐杆菌的双突变菌株。菌株NRC-1对已知的cobinamide de novo生物合成途径的中间体腺苷酸缺乏营养，但能有效地从环境中回收cobinamide，表明该古菌中存在回收途径。一株突变的盐杆菌对一种已知的新产物腺苷-哥宾酰胺- gdp缺乏营养，并且不能回收哥宾酰胺。营养分析的结果表明，cobinamide打捞的切入点是腺苷酸。该数据与cobinamide的回收途径一致，在该途径中，氨基水解酶将腺苷cobinamide的氨基丙醇部分裂解生成腺苷coby酸，腺苷coby酸被腺苷cobinamide-phosphate合成酶转化为腺苷cobinamide-phosphate，这是一种已知的新生生物合成途径的中间体。腺苷胶酰胺酰胺水解酶的存在可以解释古生菌中缺乏腺苷胶酰胺激酶的原因。
The ability of archaea to salvage cobinamide has been under question because archaeal genomes lack orthologs to the bacterial nucleoside triphosphate:5′-deoxycobinamide kinase enzyme (cobUinSalmonella enterica). The latter activity is required for cobinamide salvaging in bacteria. This paper reports evidence that archaea salvage cobinamide from the environment by using a pathway different from the one used by bacteria. These studies demanded the functional characterization of two genes whose putative function had been annotated based solely on their homology to the bacterial genes encoding adenosylcobyric acid and adenosylcobinamide-phosphate synthases (cbiPandcbiB, respectively) ofS. enterica. AcbiPmutant strain of the archaeonHalobacteriumsp. strain NRC-1 was auxotrophic for adenosylcobyric acid, a known intermediate of the de novo cobamide biosynthesis pathway, but efficiently salvaged cobinamide from the environment, suggesting the existence of a salvaging pathway in this archaeon. AcbiBmutant strain ofHalobacteriumwas auxotrophic for adenosylcobinamide-GDP, a known de novo intermediate, and did not salvage cobinamide. The results of the nutritional analyses of thecbiPandcbiBmutants suggested that the entry point for cobinamide salvaging is adenosylcobyric acid. The data are consistent with a salvaging pathway for cobinamide in which an amidohydrolase enzyme cleaves off the aminopropanol moiety of adenosylcobinamide to yield adenosylcobyric acid, which is converted by the adenosylcobinamide-phosphate synthase enzyme to adenosylcobinamide-phosphate, a known intermediate of the de novo biosynthetic pathway. The existence of an adenosylcobinamide amidohydrolase enzyme would explain the lack of an adenosylcobinamide kinase in archaea.
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