Chemoreceptor VfcA Mediates Amino Acid Chemotaxis in Vibrio fischeri
Chemoreceptor VfcA Mediates Amino Acid Chemotaxis in Vibrio fischeri
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DOI：
10.1128/aem.03794-12
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发表时间：
2013-03-01
影响因子：
4.4
通讯作者：
Mandel, Mark J.
中科院分区：
文献类型：
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作者：
Brennan, Caitlin A.;DeLoney-Marino, Cindy R.;Mandel, Mark J.
费氏弧菌的鞭毛运动和趋化性是介导其共生宿主夏威夷短尾乌贼定植的重要行为。然而，费氏弧菌基因组中编码的 43 种推定的甲基接受趋化蛋白 (MCP) 此前尚未被表征。利用可用的转座子突变体集合和定向诱变，我们分离了其中 19 个基因的突变体，并筛选了它们对六种先前鉴定的化学引诱剂的趋化性改变。只有一种突变体对任何测试化合物的反应有缺陷；因此，被破坏的基因被命名为 vfcA（费氏弧菌化学感受器 A；基因座标签 VF_0777）。在软琼脂平板中，在 vfcA 中破坏的突变体不表现出丝氨酸感应趋化环，并且突变体中的迁移模式不受添加外源丝氨酸的影响。使用毛细管趋化性测定，我们发现，与野生型费氏弧菌不同，vfcA突变体不会对丝氨酸产生趋化性，并且突变体中质粒上vfcA的表达足以恢复行为。除了丝氨酸之外，我们还证明丙氨酸、半胱氨酸和苏氨酸是野生型费氏弧菌的强引诱剂，并且这种引诱也是由 VfcA 介导的。因此，这项研究首次揭示了 V. fischeri 如何整合来自 43 个 MCP 之一的信息来响应环境刺激。
Flagellar motility and chemotaxis by Vibrio fischeri are important behaviors mediating the colonization of its mutualistic host, the Hawaiian bobtail squid. However, none of the 43 putative methyl-accepting chemotaxis proteins (MCPs) encoded in the V. fischeri genome has been previously characterized. Using both an available transposon mutant collection and directed mutagenesis, we isolated mutants for 19 of these genes, and screened them for altered chemotaxis to six previously identified chemoattractants. Only one mutant was defective in responding to any of the tested compounds; the disrupted gene was thus named vfcA (Vibrio fischeri chemoreceptor A; locus tag VF_0777). In soft-agar plates, mutants disrupted in vfcA did not exhibit the serine-sensing chemotactic ring, and the pattern of migration in the mutant was not affected by the addition of exogenous serine. Using a capillary chemotaxis assay, we showed that, unlike wild-type V. fischeri, the vfcA mutant did not undergo chemotaxis toward serine and that expression of vfcA on a plasmid in the mutant was sufficient to restore the behavior. In addition to serine, we demonstrated that alanine, cysteine, and threonine are strong attractants for wild-type V. fischeri and that the attraction is also mediated by VfcA. This study thus provides the first insights into how V. fischeri integrates information from one of its 43 MCPs to respond to environmental stimuli.