title: Conserved features and major differences in the outer membrane protein composition of chlamydiae.
abstract: Chlamydiae are a highly successful group of obligate intracellular bacteria infecting a variety of eukaryotic hosts. Outer membrane proteins involved in attachment to and uptake into host cells, and cross-linking of these proteins via disulfide bonds are key features of the biphasic chlamydial developmental cycle. In this study, we used a consensus approach to predict outer membrane proteins in the genomes of members of three chlamydial families. By analysing outer membrane protein fractions of purified chlamydiae with highly sensitive mass spectrometry, we show that the protein composition differs strongly between these organisms. Large numbers of major outer membrane protein-like proteins are present at high abundance in the outer membrane of Simkania negevensis and Waddlia chondrophila, whereas yet uncharacterized putative porins dominate in Parachlamydia acanthamoebae. Simkania represents the first case of a chlamydia completely lacking stabilizing cysteine-rich proteins in its outer membrane. In agreement with this, and in contrast to Parachlamydia and Waddlia, the cellular integrity of Simkania is not impaired by conditions that reduce disulfide bonds of these proteins. The observed differences in the protein composition of the outer membrane among members of divergent chlamydial families suggest different stabilities of these organisms in the environment, probably due to adaption to different niches or transmission routes.
authors.affiliation: Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria.
authors.forename: Karin
authors.initials: K
authors.lastname: Aistleitner
authors.forename: Dorothea
authors.initials: D
authors.lastname: Anrather
authors.forename: Thomas
authors.initials: T
authors.lastname: Schott
authors.forename: Julia
authors.initials: J
authors.lastname: Klose
authors.forename: Monika
authors.initials: M
authors.lastname: Bright
authors.forename: Gustav
authors.initials: G
authors.lastname: Ammerer
authors.forename: Matthias
authors.initials: M
authors.lastname: Horn
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002689:Chlamydia / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D017124:Conserved Sequence; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D001425:Bacterial Outer Membrane Proteins