CAMPYLOBACTER FETUS SURFACE LAYER PROTEIN SECRETION

描述(改编自申请人的摘要)：胎儿弯曲杆菌是 牛和人类免疫系统受损的重要病原体。其中一个 弓形虫的主要毒力因子是其表层(S层)。 使其能够抵抗正常和免疫血清的杀菌作用。 尽管在理解黄斑狼疮的分子机制方面取得了重大进展 表层蛋白(SLP)的抗原性变异 S层)，直到最近，人们对其分泌和组装知之甚少 SLP的数量。初步数据现在显示，胎儿SLP是通过 I型分泌系统[SAP(C)DEF]类似于识别 C末端分泌信号用于毒素、蛋白水解酶和 革兰氏阴性细菌的脂肪酶。这种关系体现在以下几个方面 胎儿SAPD突变株不能产生或分泌SLP， 提示SLP的分泌和合成之间可能存在联系。 此外，表达胎儿蛋白CDEF的大肠杆菌能够特异性地 分泌一个C胎儿SLP(SapA)，验证这些基因对 SLP分泌。SapCDEF+大肠杆菌分泌SLP的能力将是 用于描述Sapa C-末端分泌信号。 因此，研究人员建议对分泌机制进行研究。 作为胎儿SLP的一个必要组成部分，主要通过 构建了弓形虫胎儿毒力因子，并将其作为模型系统 检测异源I型转运蛋白之间的相互作用。他们 将在以下具体目标中这样做。 具体目标#1.确定SLP分泌物的成分 通过构建额外的突变来控制胎儿的器官 分泌器。SapA的潜在调节作用研究 细胞内SLP的表达将被用来研究可能的 SLP合成和分泌之间的联系。 特定目的#2.建立绒毛虫胎儿SLP分泌检测系统 在大肠杆菌中克隆了SapCDEF基因。他们将使用缺失和突变 分析确定胎儿沙门氏菌C-末端分泌信号。这个 SapA分泌调节正常细胞转运的能力 非分泌性蛋白质也将被评估。

DESCRIPTION (Adapted from the applicant's abstract): Campylobacter fetus is a significant pathogen of cattle and immunocompromised humans. One of the major virulence factors of C. fetus is its surface layer (S-layer), which allows it to resist the bactericidal effects of normal and immune serum. Despite significant advances in understanding the molecular mechanisms of antigenic variation of surface layer proteins (SLPs, the subunits of the S-layer), until recently little was known about the secretion and assembly of SLPs. Preliminary data now reveal that C. fetus SLPs are transported by a type I secretion system [Sap(C)DEF] similar to those that recognize C-terminal secretion signals for the transport of toxins, proteases and lipases from gram-negative bacteria. This relationship is demonstrated by the inability of a C. fetus sapD mutant to produce or secrete SLPs, suggesting a possible link between the secretion and synthesis of SLPs. Furthermore, E. coli expressing C. fetus sapCDEF are able to specifically secrete a C. fetus SLP (SapA), verifying the sufficiency of these genes for SLP secretion. The ability of sapCDEF+ E. coli to secrete SLPs will be exploited for the delineation of the SapA C-terminal secretion signal. The investigators therefore propose the study of the mechanism of secretion of C. fetus SLPs as a necessary component of the process by which a major virulence factor of C. fetus is assembled, and as a model system for examining the interactions between heterologous type I transporters. They will do so in the following specific aims. Specific Aim #1. To characterize the components of the SLP secretion apparatus of C. fetus through the construction of additional mutations in the secretion apparatus. Studies on the potential regulation of sapA expression by intracellular SLPs will be performed to investigate a possible link between SLP synthesis and secretion. Specific Aim #2. To construct a C. fetus SLP secretion assay system using the cloned sapCDEF genes in E. coli. They will use deletion and mutational analyses to define the C. fetus SapA C-terminal secretion signal. The ability of the SapA secretion to mediate the transport of normally non-secreted proteins also will be assessed.