The cis-diol dehydrogenase cbaC gene of Tn5271 is required for growth on 3-chlorobenzoate but not 3,4-dichlorobenzoate
The cis-diol dehydrogenase cbaC gene of Tn5271 is required for growth on 3-chlorobenzoate but not 3,4-dichlorobenzoate
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DOI：
10.1016/s0378-1119(97)00229-1
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发表时间：
1997-09-01
期刊：
影响因子：
3.5
通讯作者：
Wyndham, RC
中科院分区：
文献类型：
--
作者：
Nakatsu, CH;Providenti, M;Wyndham, RC
测定了3-氯苯甲酸（3-Cba）分解代谢转座子Tn 5271的1-羧基-3-氯-4，5-二羟基环己（顺式-二醇）脱氢酶基因cbaC的核苷酸序列。通过删除cbaC中的内部BstEII限制性位点和使用核酸外切酶III创建巢式缺失来评估推导的开放阅读框架的功能意义。用产碱杆菌属菌株BR 6024进行表达研究，所述菌株BR 6024是来自野生型分离株BR 60的氯霉素抗性色氨酸营养缺陷型。BR 6024宿主携带完整的cbnAB（3-Cba 3，4-（4，5）-双加氧酶和还原酶）基因，cbaC缺失，将3Cba代谢为顺式-4，5-二醇代谢物。这些突变体不能在3-Cba上生长，但是它们在3，4-二氯苯甲酸盐上生长，瞬时积累5-氯原儿茶酸。这些结果表明cbaC脱氢酶对于不稳定的3，4-dCba顺式-4，5-二醇代谢物的再芳构化不是必需的。建议从该代谢物中自发消除HCl以产生5-氯原儿茶酸，其是产碱杆菌属BR 60中原儿茶酸代谢裂变途径的底物。cbaC与其他15种氧化还原酶的氨基酸序列以及来自细菌、植物和动物的未知功能的序列的关系揭示了一个保守的N-末端GxxGxG双核苷酸结合结构域和一个保守的H（x（11））KHVLxEKPxA保守区，该保守区两侧是α-螺旋结构域。邻苯二甲酸顺式二醇脱氢酶（恶臭假单胞菌）、葡萄糖-果糖氧化还原酶（运动发酵单胞菌）、肌醇-2-脱氢酶（枯草芽孢杆菌）和D-半乳糖-1-脱氢酶（荧光假单胞菌）是相关蛋白。这些脱氢酶与I、II和III型脱氢酶超家族无关，所述超家族包括苯甲酸、甲苯、联苯和萘催化剂（II型）和苯催化剂（III型）中涉及的α-二醇脱氢酶。(C)1997年Elsevier Science B.V.
The nucleotide sequence of cbaC, the 1-carboxy-3-chloro-4,5-dihydroxycyclohex (cis-diol) dehydrogenase gene from the 3-chlorobenzoate (3-Cba) catabolic transposon Tn5271 was determined. The functional significance of the deduced open reading frame was evaluated by deletion of an internal BstEII restriction site in cbaC and by the creation of nested deletions using exonuclease III. Expression studies were carried out with Alcaligenes sp. strain BR6024, a chloramphenicol-resistant, tryptophan auxotroph derived from the wild-type isolate BR60. BR6024 hosts carrying complete cbnAB (3-Cba 3,4-(4,5)-dioxygenase and reductase) genes, with deletions of cbaC, metabolized 3Cba to the cis-4,5-diol metabolite. These mutants failed to grow on 3-Cba; however, they grew on 3,4-dichlorobenzoate, accumulating 5-chloroprotocatechuate transiently. These results indicated the cbaC dehydrogenase was not required for re-aromatization of the unstable 3,4-dCba cis-4,5-diol metabolite. Spontaneous elimination of HCl from this metabolite is proposed to generate 5-chloroprotocatechuate, which is a substrate for the protocatechuate metaring fission pathway in Alcaligenes sp. BR60. The relationship of the deduced amino acid sequence of cbaC with 15 other oxidoreductases and sequences of unknown function from bacteria, plants and animals revealed a conserved N-terminal GxxGxG dinucleodde-binding domain and a conserved region with a H(x(11))KHVLxEKPxA consensus flanked by alpha-helical domains. o-Phthalate cis-diol dehydrogenase (Pseudomonas putida), glucose-fructose oxidoreductase (Zymomonas mobilis), myo-inositol-2-dehydrogenase (Bacillus subtilis) and D-galactose-1-dehydrogenase (Pseudomonas fluorescens) are related proteins. These dehydrogenases are unrelated to the Type I, II and III dehydrogenase superfamilies that include the cts-diol dehydrogenases involved in benzoate, toluene, biphenyl and naphthalene catabolism (Type II) and benzene catabolism (Type III). (C) 1997 Elsevier Science B.V.