A molecular switch of the type III secretion system in Chlamydia trachomatis

沙眼衣原体III型分泌系统的分子开关专性细胞内细菌沙眼衣原体是世界上最常见的性传播疾病的病原体，是一个重大的公共卫生负担。女性生殖器衣原体感染的严重后遗症包括盆腔炎、异位妊娠和输卵管不孕。沙眼衣原体的一个关键毒力机制是III型分泌系统（T3SS），它直接将蛋白效应器传递到宿主细胞质中，破坏宿主免疫，使细菌在宿主中存活。本项目旨在研究沙眼衣原体控制III型分泌和基因表达参与疾病发病的机制。我们假设，在沙眼衣原体感染过程中，T3SS的活性受到由CT663及其蛋白伙伴组成的分子开关的调控，并与基因转录偶联。我们的新发现有力地支持了这一假设，即衣原体CT663是一种双功能蛋白，既作为转录调节剂，又与RNA聚合酶相互作用。66和CopN的T3SS伴侣，它是T3SS的调节因子和效应因子。我们的具体目标是：目标1。为了验证CT663形成III型分泌活性所必需的蛋白质复合物的假设。我们将利用蛋白质-蛋白质相互作用、免疫检测和肠致病性大肠杆菌（EPEC）系统的定量分析来表征CT663及其伙伴的动态相互作用，以及这些相互作用如何影响分泌活性。目标2。为了验证CT663对基因转录有差异调控的假设。这个目标将

DESCRIPTION (provided by applicant): A molecular switch of the type III secretion system in Chlamydia trachomatis The obligate intracellular bacterium C. trachomatis is the causative agent of the most common sexually transmitted disease worldwide and represents a significant public health burden. The severe sequelae of genital chlamydial infections in women include pelvic inflammatory disease, ectopic pregnancy and tubal infertility. A key virulence mechanism of C. trachomatis is the type III secretion system (T3SS) that directly delivers protein effectors into the host cell cytosol to subvert host immunity and enables bacterial survival in hosts. The objective of this project is to study the mechanism by which C. trachomatis controls type III secretion and gene expression, contributing to disease pathogenesis. We hypothesize that T3SS activity is regulated and coupled to gene transcription during C. trachomatis infection by a molecular switch, consisting of CT663 and its protein partners. This hypothesis is strongly supported by our novel finding that chlamydial CT663 is a bi-functional protein acting as both a transcription regulator that interacts with RNA polymerase containing ? 66 and a T3SS chaperone for CopN, which is a regulator as well as an effector of the T3SS. Our specific aims are: Aim 1. To test the hypothesis that CT663 forms a protein complex necessary for type III secretion activity. We will characterize the dynamic interactions of CT663 and its partners, and how these interactions impact the secretion activity using quantitative assays for protein-protein interactions, immunodetection, and an enteropathogenic Escherichia coli (EPEC) system. Aim 2. To test the hypothesis that CT663 differentially regulates the gene transcription. This aim will be achieved using our established transcription assays with reconstituted ?66RNA polymerase in vitro and in E. coli. These studies will uncover how T3SS activity affects gene expression during C. trachomatis infection and vice versa. This project will provide important insights into how C. trachomatis utilizes T3SS to survive in an intracellular niche by coordinating the regulatory events of the T3SS and gene expression during infection. Our research will significantly expand current knowledge of the C. trachomatis infection process and contribute to the identification of potential drug targets for new therapies that could significantly reduce the public health burden caused by C. trachomatis infection.