title: Chlamydia trachomatis outer membrane complex protein B (OmcB) is processed by the protease CPAF.
abstract: We previously reported that the Chlamydia trachomatis outer membrane complex protein B (OmcB) was partially processed in Chlamydia-infected cells. We have now confirmed that the OmcB processing occurred inside live cells during chlamydial infection and was not due to proteolysis during sample harvesting. OmcB processing was preceded by the generation of active CPAF, a serine protease known to be able to cross the inner membrane via a Sec-dependent pathway, suggesting that active CPAF is available for processing OmcB in the periplasm. In a cell-free system, CPAF activity is both necessary and sufficient for processing OmcB. Both depletion of CPAF from Chlamydia-infected cell lysates with a CPAF-specific antibody and blocking CPAF activity with a CPAF-specific inhibitory peptide removed the OmcB processing ability of the lysates. A highly purified wild-type CPAF but not a catalytic residue-substituted mutant CPAF was sufficient for processing OmcB. Most importantly, in chlamydial culture, inhibition of CPAF with a specific inhibitory peptide blocked OmcB processing and reduced the recovery of infectious organisms. Thus, we have identified OmcB as a novel authentic target for the putative chlamydial virulence factor CPAF, which should facilitate our understanding of the roles of CPAF in chlamydial biology and pathogenesis.
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Shuping
authors.initials: S
authors.lastname: Hou
authors.forename: Lei
authors.initials: L
authors.lastname: Lei
authors.forename: Zhangsheng
authors.initials: Z
authors.lastname: Yang
authors.forename: Manli
authors.initials: M
authors.lastname: Qi
authors.forename: Quanzhong
authors.initials: Q
authors.lastname: Liu
authors.forename: Guangming
authors.initials: G
authors.lastname: Zhong
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002690:Chlamydia Infections / Q000382:microbiology*; D002692:Chlamydia trachomatis / Q000276:immunology / Q000378:metabolism* / Q000472:pathogenicity; D010450:Endopeptidases / Q000276:immunology / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D011499:Protein Processing, Post-Translational; D059748:Proteolysis; D037521:Virulence Factors
chemical_list: D001425:Bacterial Outer Membrane Proteins; C436968:OmcB protein, bacteria; D037521:Virulence Factors; D010450:Endopeptidases; C425923:CPA factor