title: Host cell Golgi anti-apoptotic protein (GAAP) and growth of Chlamydia pneumoniae.
abstract: Chlamydia pneumoniae protein CPn0809 is a type three secretion system substrate, the exact function of which in infection pathogenesis has remained unknown. In this study, we identified by yeast two-hybrid screening a potential host cell interaction partner of CPn0809, Golgi anti-apoptotic protein (GAAP), a conserved protein found in eukaryotic cells. GAAP gene is expressed at relatively constant levels and its expression remained stable also after C. pneumoniae infection. The interaction between GAAP and C. pneumoniae was suggested by transfection studies. GAAP knock-down by siRNA in infected A549 cells resulted in an increased number of C. pneumoniae genomes and growth of the bacteria as judged by quantitative PCR and inclusion counts, respectively. Silencing of GAAP did not make the A549 cells more susceptible to apoptosis per se, and infection with C. pneumoniae prevented staurosporin-induced apoptosis also in transfected cultures. Taken together, the proposed interaction between C. pneumoniae and GAAP modulates bacterial growth in A549 cells.
authors.affiliation: Haartman Institute, Department of Virology, PO Box 21, University of Helsinki, FI-00014 Helsinki, Finland.
authors.forename: Eveliina
authors.initials: E
authors.lastname: Markkula
authors.forename: Jaakko
authors.initials: J
authors.lastname: Hulkkonen
authors.forename: Tuula
authors.initials: T
authors.lastname: Penttilä
authors.forename: Mirja
authors.initials: M
authors.lastname: Puolakkainen
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002460:Cell Line; D016993:Chlamydophila pneumoniae / Q000254:growth & development* / Q000472:pathogenicity*; D004847:Epithelial Cells / Q000382:microbiology; D020868:Gene Silencing; D054884:Host-Pathogen Interactions; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D025941:Protein Interaction Mapping; D020798:Two-Hybrid System Techniques; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; C518281:TMBIM4 protein, human; D037521:Virulence Factors