Molecular function and biological importance of the protease CPAF during infection of human cells by Chlamydia

沙眼衣原体是一种专性细胞内细菌，在人类感染期间会引起感染细胞的巨大变化和实质性的病理变化。虽然已经描述了许多宿主细胞对衣原体感染的反应，但细菌效应物的分子特性尚不确定，它们对宿主细胞反应的重要性还不完全清楚。我们已经确定衣原体蛋白水解酶CPAF是宿主细胞操纵和细胞致病的重要介体。在拟议的项目中，我们的目标是从分子上了解CPAF在衣原体感染人类细胞中的作用和重要性。作为CPAF的靶点，我们的工作中出现了以下细胞系统：先天免疫信号(NF-κB，ERK)；细胞存活/细胞死亡机制；宿主细胞中的蛋白质翻译；泛素-蛋白酶体系统。考虑到新发现的人类CPAF底物和新认识的蛋白酶特性，我们将分析CPAF以什么方式改变这些系统的活性，以及在感染期间这如何影响宿主细胞。此外，已经在主要不感染人类的衣原体样细菌中发现了CPAF直系同源物。通过对这些同源基因的比较分析，将有可能获得CPAF的分子和细胞生物学活性与人类感染能力相关的信息。我们认为，了解CPAF生物学将是了解衣原体对人类致病性的重要一步。

Chlamydia trachomatis is an obligate intracellular bacterium that causes massive changes to the infected human cell and substantial pathology during human infection. Although many host cell responses to chlamydial infection have been described, the molecular identity of bacterial effectors is uncertain and their importance for the host cell response is understood only incompletely. We have identified the chlamydial protease CPAF as an important mediator of host cell manipulation and cytopathogenicity. In the proposed project we aim at a molecular understanding of the role and importance of CPAF in the infection of human cells by Chlamydia. The following cellular systems emerge from our work as targets of CPAF: innate immune signalling (NF-κB, ERK); cell viability/cell death machinery; protein translation in the host cell; the ubiquitin-proteasome system. Considering newly identified human CPAF substrates and newly recognised characteristics of the protease, we will analyse in what way CPAF alters the activity of these systems and how this affects the host cell during infection. Furthermore, CPAF orthologues have been identified in Chlamydia-like bacteria that do not primarily infect humans. By comparative analysis of these orthologues it will be possible to obtain information which molecular and cell biological activity of CPAF is associated with the capacity for human infection. We believe that understanding CPAF biology will be an important step to the appreciation of chlamydial pathogenicity in humans.