Targeting of a Chlamydial Protease Impedes Intracellular Bacterial Growth

Jan G Christian,Georg Häcker,Stefan A Paschen,Juliane Vier,Jan Rupp,Linda Schauenburg,Thomas F Meyer,Julia Heymann,Dagmar Heuer

doi:10.1371/journal.ppat.1002283

Abstract

Chlamydiae are obligate intracellular bacteria that propagate in a cytosolic vacuole. Recent work has shown that growth of Chlamydia induces the fragmentation of the Golgi apparatus (GA) into ministacks, which facilitates the acquisition of host lipids into the growing inclusion. GA fragmentation results from infection-associated cleavage of the integral GA protein, golgin-84. Golgin-84-cleavage, GA fragmentation and growth of Chlamydia trachomatis can be blocked by the peptide inhibitor WEHD-fmk. Here we identify the bacterial protease chlamydial protease-like activity factor (CPAF) as the factor mediating cleavage of golgin-84 and as the target of WEHD-fmk-inhibition. WEHD-fmk blocked cleavage of golgin-84 as well as cleavage of known CPAF targets during infection with C. trachomatis and C. pneumoniae. The same effect was seen when active CPAF was expressed in non-infected cells and in a cell-free system. Ectopic expression of active CPAF in non-infected cells was sufficient for GA fragmentation. GA fragmentation required the small GTPases Rab6 and Rab11 downstream of CPAF-activity. These results define CPAF as the first protein that is essential for replication of Chlamydia. We suggest that this role makes CPAF a potential anti-infective therapeutic target.

Highlights

Chlamydiae are a group of obligate intracellular bacteria that infect humans and animals
Recent results show that for this, Chlamydia relies on its ability to induce the loss of an individual protein of the Golgi apparatus called golgin-84
In this work we find that Chlamydia does this using its protein-cleaving enzyme chlamydial protease-like activity factor (CPAF)

Summary

Introduction

Chlamydiae are a group of obligate intracellular bacteria that infect humans and animals. Chlamydia pneumoniae is a very common cause of (typically mild) airway infection but it has been proposed to cause chronic infection of artery walls, contributing to atherosclerosis [4]. Within the inclusion EBs differentiate into reticulate bodies (RBs), which divide by binary fission. During this intracellular growth phase the inclusion substantially increases in size, often filling almost the entire cell at later time points. Towards the end of the cycle RBs re-differentiate into EBs, which are subsequently released from the cell. In vitro this cycle takes approximately 2 days for C. trachomatis and 3-4 days for C. pneumoniae [5]

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