Vibrio cholerae vciB promotes iron uptake via ferrous iron transporters
Vibrio cholerae vciB promotes iron uptake via ferrous iron transporters
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DOI：
10.1128/jb.00569-08
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发表时间：
2008-09-01
影响因子：
3.2
通讯作者：
Payne, Shelley M.
中科院分区：
文献类型：
--
作者：
Mey, Alexandra R.;Wyckoff, Elizabeth E.;Payne, Shelley M.
霍乱弧菌在其不同的环境中使用各种策略来获取铁。在本研究中，我们鉴定了霍乱弧菌中一种新的铁利用蛋白VciB。VciB基因及其连锁基因vciA是在霍乱弧菌的筛选中分离出来的，该基因允许一株大肠杆菌铁载体突变株在低铁条件下生长。VciAB操纵子编码一个依赖于TonB的外膜受体VciA和一个可能的内膜蛋白VciB。在低铁条件下，VciB而不是VciA对大肠杆菌和福氏志贺氏菌的生长有促进作用。与这些发现一致的是，VciB介导的生长不需要TonB。当vciB在缺乏亚铁转运蛋白FeO的大肠杆菌或志贺氏菌中表达时，没有观察到生长促进作用。给E.Colifeo突变体提供编码大肠杆菌或霍乱弧菌Feo的质粒，或者给S.Flexneri亚铁运输系统SIT，恢复了VciB介导的生长；然而，当霍乱弧菌FBP和流感嗜血杆菌HIT中的任何一个铁摄取系统表达时，都没有刺激作用。这些数据表明，VciB通过铁而不是铁的运输系统促进铁的吸收。在使用放射性标记铁的铁转运试验中，直接证明了VciB依赖的铁通过FeO积累。一株霍乱弧菌vciB突变体在体外和体内实验中均未表现出任何生长缺陷，这可能是由于该病原体中存在其他功能重叠的系统所致。
Vibrio cholerae uses a variety of strategies for obtaining iron in its diverse environments. In this study we report the identification of a novel iron utilization protein in V. cholerae, VciB. The vciB gene and its linked gene, vciA, were isolated in a screen for V. cholerae genes that permitted growth of an Escherichia coli siderophore mutant in low-iron medium. The vciAB operon encodes a predicted TonB-dependent outer membrane receptor, VciA, and a putative inner membrane protein, VciB. VciB, but not VciA, was required for growth stimulation of E. coli and Shigella flexneri strains in low-iron medium. Consistent with these findings, TonB was not needed for VciB-mediated growth. No growth enhancement was seen when vciB was expressed in an E. coli or S. flexneri strain defective for the ferrous iron transporter Feo. Supplying the E. coli feo mutant with a plasmid encoding either E. coli or V. cholerae Feo, or the S. flexneri ferrous iron transport system Sit, restored VciB-mediated growth; however, no stimulation was seen when either of the ferric uptake systems V. cholerae Fbp and Haemophilus influenzae Hit was expressed. These data indicate that VciB functions by promoting iron uptake via a ferrous, but not ferric, iron transport system. VciB-dependent iron accumulation via Feo was demonstrated directly in iron transport assays using radiolabeled iron. A V. cholerae vciB mutant did not exhibit any growth defects in either in vitro or in vivo assays, possibly due to the presence of other systems with overlapping functions in this pathogen.