Control of virulence protein export in Yersinia pestis

描述(由申请人提供)：鼠疫耶尔森氏菌III型分泌系统(T3SS)的功能是将抗宿主蛋白YOPs直接注入目标真核细胞的细胞质中。注射过程可分为三个不同的步骤：(1)将细菌附着在真核细胞上；(2)跨细菌内膜和外膜分泌YOPs；(3)跨真核膜转位YOPs。在这笔赠款的支持下，我们实验室的工作重点是T3S过程的调节。YOP的分泌是通过在体内接触真核细胞或在体外无细胞外钙的情况下生长而触发的。细胞内的YopN/SycN/YscB/TyeA复合体需要在有钙存在的情况下以及在与真核细胞接触之前阻断Yop的分泌。细菌感知这些细胞外信号并将这些信息传输到细胞质隔间的机制尚不清楚。我们最近已经证明，表面定位的YscF针是调节YOP分泌所必需的。我们假设YscF针和针相关蛋白(LcrV针尖复合体和Yscl杆结构)的部分功能是感知细胞外信号，将这些信息传递到细胞室，并调节分子插头(YopN/SycN/YscB/TyeA复合体)的活性。这项拟议的研究旨在更好地了解控制YOP分泌的调控事件。具体地说，我们将(I)阐明YopN/SycN/YscB/TyeA复合体阻断分泌的分子机制；(Ii)研究Yscl杆、YscF针和LcrV尖端复合体在Yop分泌调节中的作用。这些研究将促进我们对调节鼠疫杆菌和其他重要病原体中T3S的分子事件的理解。

DESCRIPTION (provided by applicant): The Yersinia pestis type III secretion system (T3SS) functions to inject anti-host proteins, termed Yops, directly into the cytoplasm of targeted eukaryotic cells. The injection process can be divided into three distinct steps: (i) attachment of the bacteria to a eukaryotic cell; (ii) secretion of Yops across the bacterial inner and outer membranes; and (iii) translocation of Yops across a eukaryotic membrane. Work in our laboratory supported by this Grant has focused on the regulation of the T3S process. Yop secretion is triggered by contact with a eukaryotic cell in vivo or by growth in the absence of extracellular calcium in vitro. A cytosolic YopN/SycN/YscB/TyeA complex is required to block Yop secretion in the presence of calcium and prior to contact with a eukaryotic cell. The mechanism by which the bacterium senses these extracellular signals and transmits this information to the cytosolic compartment is not known. We have recently demonstrated that the surface-localized YscF needle is required to regulate Yop secretion. We hypothesize that the YscF needle and needle-associated proteins (the LcrV needle tip complex and Yscl rod structure) function, in part, to sense extracellular signals, transmit this information to the cytosolic compartment and regulate the activity of a molecular plug (the YopN/SycN/YscB/TyeA complex). The proposed research is aimed at gaining a better understanding of the regulatory events that control Yop secretion. Specifically, we will (i) elucidate the molecular mechanism by which the YopN/SycN/YscB/TyeA complex blocks secretion and (ii) investigate the role of the Yscl rod, the YscF needle and the LcrV tip complex in the regulation of Yop secretion. These studies will advance our understanding of the molecular events that regulate T3S in Y. pestis and in other important pathogens.