Arsenite oxidase aox genes from a metal-resistant β-proteobacterium
Arsenite oxidase aox genes from a metal-resistant β-proteobacterium
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DOI：
10.1128/jb.185.1.135-141.2003
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发表时间：
2003-01-01
影响因子：
3.2
通讯作者：
Lett, MC
中科院分区：
文献类型：
--
作者：
Muller, D;Lièvremont, D;Lett, MC
从砷污染环境中分离到的β-蛋白细菌ULPAs1能够有效地将亚砷酸盐[As(III)]氧化为砷[As(V)]。用基于LacZ的报告转座子进行突变，产生了两个缺乏亚砷酸盐氧化的敲除衍生物。对两个突变体转座子插入两侧的DNA进行序列分析，确定了两个相邻的开放阅读框，命名为aoxA和aoxB，以及aoxA基因上游的一个假定启动子。逆转录-聚合酶链式反应结果表明，这些基因是以操纵子结构组织起来的。AoxA和AoxB编码的蛋白与粪产碱菌纯化和结晶的亚砷酸氧化酶的Rieske小亚基和大亚基的同源性分别为72%和72%(P.J.Ellis，T.Conrads，R.Hille和P.Kuhn，Structure[剑桥]9：125-132,2001)。重要的是，几乎所有参与粪链霉菌酶两个亚基中的辅因子相互作用的氨基酸在ULPAs1菌株的相应序列中都是保守的。在AoxA编码的蛋白质的N端还检测到一个额外的TAT(双精氨酸转位)信号肽序列，这强烈表明TAT途径参与了亚砷酸氧化酶向其已知的周质位置的转位。
The beta-proteobacterial strain ULPAs1, isolated from an arsenic-contaminated environment, is able to efficiently oxidize arsenite [As(III)] to arsenate [As(V)]. Mutagenesis with a lacZ-based reporter transposon yielded two knockout derivatives deficient in arsenite oxidation. Sequence analysis of the DNA flanking the transposon insertions in the two mutants identified two adjacent open reading frames, named aoxA and aoxB, as well as a putative promoter upstream of the aoxA gene. Reverse transcription-PCR data indicated that these genes are organized in an operonic structure. The proteins encoded by aoxA and aoxB share 64 and 72% identity with the small Rieske subunit and the large subunit of the purified and crystallized arsenite oxidase of Alcaligenes faecalis, respectively (P. J. Ellis, T. Conrads, R. Hille, and P. Kuhn, Structure [Cambridge] 9:125-132, 2001). Importantly, almost all amino acids involved in cofactor interactions in both subunits of the A. faecalis enzyme were conserved in the corresponding sequences of strain ULPAs1. An additional Tat (twin-arginine translocation) signal peptide sequence was detected at the N terminus of the protein encoded by aoxA, strongly suggesting that the Tat pathway is involved in the translocation of the arsenite oxidase to its known periplasmic location.