The Opportunistic Pathogen Serratia marcescens Utilizes Type VI Secretion To Target Bacterial Competitors
The Opportunistic Pathogen Serratia marcescens Utilizes Type VI Secretion To Target Bacterial Competitors
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DOI：
10.1128/jb.05671-11
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发表时间：
2011-11-01
影响因子：
3.2
通讯作者：
Coulthurst, Sarah J.
中科院分区：
文献类型：
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作者：
Murdoch, Sarah L.;Trunk, Katharina;Coulthurst, Sarah J.
VI型分泌系统（T6SS）是革兰氏阴性菌中最新描述和了解最少的蛋白质分泌系统。它分布广泛，并与各种病原体的毒力有关，但其作用机制和确切模式仍有待确定。此外，最近有几份报告称，一些T6SS可以靶向细菌而不是真核细胞。粘质沙雷氏菌是一种机会性肠道病原体，是一类引起很大比例医院获得性感染的细菌。我们描述了在S. marcescens菌株Db 10，第一次报告VI型分泌的机会主义肠道细菌。对S. marcescens Db 10是有活性的，分泌到培养基中的HCP容易被检测到，并且在正常生长条件下从一个大的转录单位组成型表达。T6SS基因的表达似乎不依赖于T6SS的完整性。色葡萄粘质杆菌Db10 T6SS在三种非哺乳动物毒力模型中的毒力不是必需的。然而，它确实对其他几种细菌表现出显着的抗菌活性，并且是S.粘质杆菌与另一种机会致病菌阴沟肠杆菌混合培养。重要的是，这种抗菌活性是高度菌株特异性的，S。marcescens Db10 T6SS对另一株S. marcescens具有非常相似且活性的T6SS。我们的结论是，VI型分泌起着至关重要的作用，在竞争力，从而间接的毒力，S。粘质杆菌和其它机会性细菌病原体。
The type VI secretion system (T6SS) is the most recently described and least understood of the protein secretion systems of Gram-negative bacteria. It is widely distributed and has been implicated in the virulence of various pathogens, but its mechanism and exact mode of action remain to be defined. Additionally there have been several very recent reports that some T6SSs can target bacteria rather than eukaryotic cells. Serratia marcescens is an opportunistic enteric pathogen, a class of bacteria responsible for a significant proportion of hospital-acquired infections. We describe the identification of a functional T6SS in S. marcescens strain Db10, the first report of type VI secretion by an opportunist enteric bacterium. The T6SS of S. marcescens Db10 is active, with secretion of Hcp to the culture medium readily detected, and is expressed constitutively under normal growth conditions from a large transcriptional unit. Expression of the T6SS genes did not appear to be dependent on the integrity of the T6SS. The S. marcescens Db10 T6SS is not required for virulence in three nonmammalian virulence models. It does, however, exhibit dramatic antibacterial killing activity against several other bacterial species and is required for S. marcescens to persist in a mixed culture with another opportunist pathogen, Enterobacter cloacae. Importantly, this antibacterial killing activity is highly strain specific, with the S. marcescens Db10 T6SS being highly effective against another strain of S. marcescens with a very similar and active T6SS. We conclude that type VI secretion plays a crucial role in the competitiveness, and thus indirectly the virulence, of S. marcescens and other opportunistic bacterial pathogens.