Bacterial cyanide oxygenase is a suite of enzymes catalyzing the scavenging and adventitious utilization of cyanide as a nitrogenous growth substrate
Bacterial cyanide oxygenase is a suite of enzymes catalyzing the scavenging and adventitious utilization of cyanide as a nitrogenous growth substrate
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DOI：
10.1128/jb.187.18.6396-6402.2005
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发表时间：
2005-09-01
影响因子：
3.2
通讯作者：
Kunz, DA
中科院分区：
文献类型：
--
作者：
Fernandez, RF;Kunz, DA
荧光假单胞菌NCIMB 11764的氰化物加氧酶（CNO）催化羽翼蛋白依赖的氰化物（CN）氧化裂解为甲酸和氨。CNO被分解成四种蛋白质组分（P1至P4），每种组分都与pterin辅助因子源一起是CNO活性所必需的。组分P1是一个多聚体230 kda的黄蛋白，具有形成过氧化物的NADH氧化酶（氧化还原酶）（Nox）的特性。P2由49.7 kda的同型二聚体组成，其N端显示100%的氨基酸同源性，来自粪肠球菌的NADH过氧化物酶（Npx）。酶分析进一步证实了Nox和Npx酶的特性（比活性为1 U/mg）。P3是一个大的寡聚蛋白（约300 kDa），具有氰化物二水合酶（CynD）活性（比活性为100 U/mg）。在分离的酶中分别检测到38 kDa和43 kDa的两个多肽，前者被认为具有催化活性，基于其与其他CynD酶相似的大小。43-kDa蛋白内部肽的氨基酸序列与细菌延伸因子Tu完全相同，表明它可能在CynD或多酶CNO复合物的组装中起伴侣作用。剩余P4组分为28.9 kda的同二聚体，鉴定为碳酸酐酶（比活性为2000 U/mg）。虽然参与pterin的功能以及Nox、Npx、CynD和CA在CN催化清除CN中的作用仍有待确定，但这是首次报道这四种酶共同参与CN作为细菌氮生长底物的代谢解毒和利用。
Cyanide oxygenase (CNO) from Pseudomonas fluorescens NCIMB 11764 catalyzes the pterin-dependent oxygenolytic cleavage of cyanide (CN) to formic acid and ammonia. CNO was resolved into four protein components (P1 to P4), each of which along with a source of pterin cofactor was obligately required for CNO activity. Component P1 was characterized as a multimeric 230-kDa flavoprotein exhibiting the properties of a peroxide-forming NADH oxidase (oxidoreductase) (Nox). P2 consisted of a 49.7-kDa homodimer that showed 100% amino acid identity at its N terminus to NADH peroxidase (Npx) from Enterococcus faecalis. Enzyme assays further confirmed the identities of both Nox and Npx enzymes (specific activity, 1 U/mg). P3 was characterized as a large oligomeric protein (similar to 300 kDa) that exhibited cyanide dihydratase (CynD) activity (specific activity, 100 U/mg). Two polypeptides of 38 kDa and 43 kDa were each detected in the isolated enzyme, the former believed to confer catalytic activity based on its similar size to other CynD enzymes. The amino acid sequence of an internal peptide of the 43-kDa protein was 100% identical to bacterial elongation factor Tu, suggesting a role as a possible chaperone in the assembly of CynD or a multienzyme CNO Complex. The remaining P4 component consisted of a 28.9-kDa homodimer and was identified as carbonic anhydrase (specific activity, 2,000 U/mg). While the function of participating pterin and the roles of Nox, Npx, CynD, and CA in the CNO-catalyzed scavenging of CN remain to be determined, this is the first report describing the collective involvement of these four enzymes in the metabolic detoxification and utilization of CN as at bacterial nitrogenous growth substrate.