The Yersinia pestis type III secretion needle plays a role in the regulation of Yop secretion
The Yersinia pestis type III secretion needle plays a role in the regulation of Yop secretion
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DOI：
10.1111/j.1365-2958.2005.04790.x
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发表时间：
2005-09-01
影响因子：
3.6
通讯作者：
Plano, GV
中科院分区：
文献类型：
--
作者：
Torruellas, J;Jackson, MW;Plano, GV
细菌毒力相关的III型分泌系统(T3SS)的激活需要细菌和真核细胞之间的直接接触。在鼠疫耶尔森氏菌中，胞内的LcrG蛋白和胞内的YopN-TyeA复合体在细胞外钙存在的情况下，在与真核细胞接触之前阻止T3S的功能。细菌感知细胞外钙和/或细胞接触并将这些信号传输到胞质隔间的机制尚不清楚。我们在这里报道了YscF，一种聚合形成T3SS外针的小蛋白，对于T3S的钙依赖调节是必不可少的。丙氨酸扫描突变被用来鉴定YscF突变体，这些突变体在有钙和无钙的情况下以及在接触真核细胞之前分泌毒力蛋白。有趣的是，其中一个YscF突变体表现出组成T3S，但不能将分泌的蛋白质转移到真核细胞质膜上。这些数据表明，YscF针是一个多功能结构，参与毒力蛋白的分泌，毒力蛋白跨真核细胞膜的转运，以及T3S的细胞接触和钙依赖的调节。
Activation of bacterial virulence-associated type III secretion systems (T3SSs) requires direct contact between a bacterium and a eukaryotic cell. In Yersinia pestis, the cytosolic LcrG protein and a cytosolic YopN-TyeA complex function to block T3S in the presence of extracellular calcium and prior to contact with a eukaryotic cell. The mechanism by which the bacterium senses extracellular calcium and/or cell contact and transmits these signals to the cytosolic compartment is unknown. We report here that YscF, a small protein that polymerizes to form the external needle of the T3SS, is essential for the calcium-dependent regulation of T3S. Alanine-scanning mutagenesis was used to identify YscF mutants that secrete virulence proteins in the presence and absence of calcium and prior to contact with a eukaryotic cell. Interestingly, one of the YscF mutants that exhibited constitutive T3S was unable to translocate secreted proteins across the eukaryotic plasma membrane. These data indicate that the YscF needle is a multifunctional structure that participates in virulence protein secretion, in translocation of virulence proteins across eukaryotic membranes and in the cell contact- and calcium-dependent regulation of T3S.