Establishment and maintenance of the chlamydial inclusion: requirement for septins and the inhibition of host cell translation

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Chlamydia trachomatis, a frequent agent of human eye infection and sexually transmitted disease, is an obligate intracellular bacterium that grows in a membrane-bounded vacuole (the inclusion) in the cytoplasm of the human host cell. Unlike other pathogen-containing vacuoles, the Chlamydia-inclusion lacks markers of endocytic transport but acquires components from the post-Golgi exocytic vesicular pathway. Chlamydia induces fragmentation of the Golgi apparatus through cleavage of the Golgi-matrix protein golgin-84, and this has been linked to lipid acquisition by the inclusion. We have recently shown that the Chlamydia protease CPAF cleaves golgin-84 and that ectopically expressed CPAF is sufficient to induce Golgi-fragmentation. Further, the synthetic caspase-1-inhibitor WEHDfmk was identified as an inhibitor of CPAF. In this project we aim at understanding mechanism and importance of this function of CPAF. CPAF will be either specifically inhibited during infection or ectopically expressed. The effect of these experimental manipulations on vesicular transport, transport to the inclusion and the development of inclusion and bacteria will be monitored using cell biological as well as proteomic and lipidomic approaches. The evolutionary conservation of this mechanism will further be tested by the analysis of CPAF from species of Chlamydia-like organisms. These studies will enhance our understanding of maintenance and development of the chlamydial inclusion and the mechanisms and importance of the hijacking of the post-Golgi exocytic pathway by an intracellular pathogen.