title: Identification and characterization of Inc766, an inclusion membrane protein in Chlamydophila abortus-infected cells.
abstract: We have identified the gene product of locus 766 in the transmembrane head region (TMH/Inc-region) in the Chlamydophila abortus genome by using mass spectrometry and a monoclonal antibody that reacted with the inclusion membrane. The identified protein at 32 kDa, termed Inc766, formed highly stable oligomers when solubilized in the absence of beta-mercaptoethanol. These oligomers were resistant to SDS, to heat denaturation and to 8M urea, but very sensitive to beta-mercaptoethanol, consistent with conformations resulting from protein-protein interactions stabilized through disulphide bonds. Mass spectrometry analysis of immunoprecipitated infected cell lysates indicated that a dimer at 56 kDa was the most prominent form in solution. Cross-linking with DSP provided supporting evidence for the formation of oligomers in situ. Inc766 was expressed at 20-24h post infection and its localization pattern in the extra-inclusion space was common in all C. abortus strains tested. Taken together, Inc766 displays unique biochemical and cellular features not encountered in other Incs from other Chlamydiaceae species. Future studies of the particular characteristics especially the interactive properties of Inc766 should contribute to our understanding of the relationship of the different chlamydial species with their respective hosts.
authors.affiliation: Laboratory of Biotechnology, Department of Microbiology, Hellenic Pasteur Institute, 127 Vassilissis Sofias Avenue, 11521 Athens, Greece. vretou@pasteur.gr
authors.forename: Evangelia
authors.initials: E
authors.lastname: Vretou
authors.forename: Evangelia
authors.initials: E
authors.lastname: Katsiki
authors.forename: Evgenia
authors.initials: E
authors.lastname: Psarrou
authors.forename: Kostantinos
authors.initials: K
authors.lastname: Vougas
authors.forename: George Th
authors.initials: GT
authors.lastname: Tsangaris
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D023501:Chlamydophila / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D023521:Chlamydophila Infections / Q000382:microbiology*; D006801:Humans; D002479:Inclusion Bodies / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins