title: Role for chlamydial inclusion membrane proteins in inclusion membrane structure and biogenesis.
abstract: The chlamydial inclusion membrane is extensively modified by the insertion of type III secreted effector proteins. These inclusion membrane proteins (Incs) are exposed to the cytosol and share a common structural feature of a long, bi-lobed hydrophobic domain but little or no primary amino acid sequence similarity. Based upon secondary structural predictions, over 50 putative inclusion membrane proteins have been identified in Chlamydia trachomatis. Only a limited number of biological functions have been defined and these are not shared between chlamydial species. Here we have ectopically expressed several C. trachomatis Incs in HeLa cells and find that they induce the formation of morphologically distinct membranous vesicular compartments. Formation of these vesicles requires the bi-lobed hydrophobic domain as a minimum. No markers for various cellular organelles were observed in association with these vesicles. Lipid probes were incorporated by the Inc-induced vesicles although the lipids incorporated were dependent upon the specific Inc expressed. Co-expression of Inc pairs indicated that some colocalized in the same vesicle, others partially overlapped, and others did not associate at all. Overall, it appears that Incs may have an intrinsic ability to induce membrane formation and that individual Incs can induce membranous structures with unique properties.
authors.affiliation: Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Mital
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Miller
authors.forename: David W
authors.initials: DW
authors.lastname: Dorward
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Dooley
authors.forename: Ted
authors.initials: T
authors.lastname: Hackstadt
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D021961:Cell Membrane Structures / Q000378:metabolism*; D002692:Chlamydia trachomatis; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D002479:Inclusion Bodies / Q000378:metabolism / Q000648:ultrastructure; D007425:Intracellular Membranes / Q000378:metabolism; D008563:Membrane Lipids; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport
chemical_list: D001426:Bacterial Proteins; D008563:Membrane Lipids; D008565:Membrane Proteins