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首页> 美国卫生研究院文献>Infection and Immunity >All Three TonB Systems Are Required for Vibrio vulnificus CMCP6 Tissue Invasiveness by Controlling Flagellum Expression
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All Three TonB Systems Are Required for Vibrio vulnificus CMCP6 Tissue Invasiveness by Controlling Flagellum Expression

机译：通过控制鞭毛表达所有三个TonB系统都需要用于创伤弧菌CMCP6组织侵袭

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摘要

TonB systems actively transport iron-bound substrates across the outer membranes of Gram-negative bacteria. Vibrio vulnificus CMCP6, which causes fatal septicemia and necrotizing wound infections, possesses three active TonB systems. It is not known why V. vulnificus CMCP6 has maintained three TonB systems throughout its evolution. The TonB1 and TonB2 systems are relatively well characterized, while the pathophysiological function of the TonB3 system is still elusive. A reverse transcription-PCR (RT-PCR) study showed that the tonB1 and tonB2 genes are preferentially induced in vivo, whereas tonB3 is persistently transcribed, albeit at low expression levels, under both in vitro and in vivo conditions. The goal of the present study was to elucidate the raison d'être of these three TonB systems. In contrast to previous studies, we constructed in-frame single-, double-, and triple-deletion mutants of the entire structural genes in TonB loci, and the changes in various virulence-related phenotypes were evaluated. Surprisingly, only the tonB123 mutant exhibited a significant delay in killing eukaryotic cells, which was complemented in trans with any TonB operon. Very interestingly, we discovered that flagellum biogenesis was defective in the tonB123 mutant. The loss of flagellation contributed to severe defects in motility and adhesion of the mutant. Because of the difficulty of making contact with host cells, the mutant manifested defective RtxA1 toxin production, which resulted in impaired invasiveness, delayed cytotoxicity, and decreased lethality for mice. Taken together, these results indicate that a series of virulence defects in all three TonB systems of V. vulnificus CMCP6 coordinately complement each other for iron assimilation and full virulence expression by ensuring flagellar biogenesis.
机译：TonB系统可将铁结合的底物主动转移到革兰氏阴性细菌的外膜上。引起致命败血病和坏死性伤口感染的创伤弧菌CMCP6具有三个活跃的TonB系统。尚不知道为什么V. vulnificus CMCP6在其整个进化过程中都维持了三个TonB系统。 TonB1和TonB2系统的特征相对较好，而TonB3系统的病理生理功能仍然难以捉摸。逆转录-PCR（RT-PCR）研究表明，在体内和体外条件下，tonB1和tonB2基因在体内均被优先诱导，而tonB3则在低表达水平下被持续转录。本研究的目的是阐明这三个TonB系统的存在理由。与以前的研究相反，我们构建了TonB基因座中整个结构基因的框内单，双和三缺失突变体，并评估了各种毒力相关表型的变化。出人意料的是，只有tonB123突变体在杀死真核细胞方面显示出显着的延迟，这与任何TonB操纵子反式互补。非常有趣的是，我们发现tonB123突变体的鞭毛生物发生有缺陷。鞭毛的丧失导致突变体的运动性和粘附性严重缺陷。由于难以与宿主细胞接触，该突变体表现出缺陷的RtxA1毒素产生，从而导致侵袭力受损，细胞毒性延迟以及对小鼠的致死率降低。综上所述，这些结果表明，通过确保鞭毛生物发生，V。vulnificus CMCP6的所有三个TonB系统中的一系列毒力缺陷在铁同化和完全毒力表达方面相互协调互补。

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