title: Characterization of the hypothetical protein Cpn1027, a newly identified inclusion membrane protein unique to Chlamydia pneumoniae.
abstract: The hypothetical protein Cpn1027 was detected in the inclusion membrane of Chlamydia pneumoniae-infected cells with antibodies raised with Cpn1027 fusion proteins in an indirect immunofluorescence assay. The inclusion membrane staining by the anti-Cpn1027 antibodies co-localized with the staining of an antibody recognizing a known inclusion membrane protein designated IncA and these membrane stainings were blocked by the corresponding but not irrelevant fusion proteins. Although Cpn1027 was not predicted to be an inclusion membrane protein, it contained a bi-lobed hydrophobic domain region at its N-terminus, a signature secondary structural motif possessed by most chlamydial inclusion membrane proteins. The Cpn1027 protein was detected as early as 12 h after C. pneumoniae infection and remained in the inclusion membrane throughout the rest of the infection cycle. Cytosolic expression of Cpn1027 via a transgene failed to affect the subsequent chlamydial infection. The anti-Cpn1027 polyclonal antisera failed to detect any significant signals in cells infected with chlamydial species other than C. pneumoniae, which is consistent with the sequence analysis result that no significant homologues of Cpn1027 were found in any other species. These experiments together have demonstrated that Cpn1027 is a newly identified inclusion membrane protein unique to C. pneumoniae.
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
authors.forename: Rhonda
authors.initials: R
authors.lastname: Flores
authors.forename: Jianhua
authors.initials: J
authors.lastname: Luo
authors.forename: Ding
authors.initials: D
authors.lastname: Chen
authors.forename: Gracie
authors.initials: G
authors.lastname: Sturgeon
authors.forename: Pooja
authors.initials: P
authors.lastname: Shivshankar
authors.forename: Youmin
authors.initials: Y
authors.lastname: Zhong
authors.forename: Guangming
authors.initials: G
authors.lastname: Zhong
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D016993:Chlamydophila pneumoniae / Q000737:chemistry* / Q000378:metabolism; D002479:Inclusion Bodies / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D017433:Protein Structure, Secondary
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins