Localization and characterization of two putative TMH family proteins in Chlamydia psittaci

• Published in: Microbiological research 2016-02, Vol.183, p.19-25
• Main Authors: Wu, Haiying, Wang, Chuan, Jiang, Chuanhao, Xie, Yafeng, Liu, Liangzhuan, Song, Ying, Ma, Xiaohua, Wu, Yimou
• Format: Article
• Language: English
• Subjects: Bacterial Outer Membrane Proteins - genetics; Bacterial Outer Membrane Proteins - isolation & purification; Bacterial Outer Membrane Proteins - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - immunology; Bacterial Proteins - isolation & purification; Bacterial Proteins - pharmacology; Chlamydia Infections - diagnosis; Chlamydia Infections - immunology; Chlamydia Infections - microbiology; Chlamydia psittaci; Chlamydia trachomatis; Chlamydophila pneumoniae; Chlamydophila psittaci - genetics; Chlamydophila psittaci - metabolism; Cloning, Molecular; CPSIT_0844; CPSIT_0846; Cytokines - biosynthesis; Escherichia coli; Escherichia coli - genetics; Fluorescent Antibody Technique - methods; Genes, Bacterial; HeLa Cells; Humans; Immune Sera - immunology; Immune Sera - isolation & purification; Inclusion membrane protein; Psittacosis - microbiology; Putative TMH family protein; Recombinant Proteins - genetics; Tumor Necrosis Factor-alpha - biosynthesis
• ISSN: 0944-5013; 1618-0623
• DOI: 10.1016/j.micres.2015.11.005

Chlamydia psittaci (C. psittaci), an obligate intracellular agent of psittacosis, causes an atypical pneumonia in humans. The transmembrane head proteins (TMH) of C. psittaci, putatively belong to the Inc family and presumably play similar roles. CPSIT_0844 and CPSIT_0846 were the putative TMH proteins of C. psittaci. To identify these two proteins, antisera were raised with fusion proteins which were prokaryotic expressed in Escherichia coli and purified. By immunofluorescence assay, CPSIT_0844 and CPSIT_0846 were localized in the inclusion membrane of C. psittaci-infected cells. By RT-PCR and western blot analysis to detect the temporal expression, CPSIT_0844 and CPSIT_0846 were detected as early as 12h post-infection (p.i.) and 6h p.i., separately; meanwhile, in secretions monitored with immunofluorescence assay, these proteins were observed in the inclusion membrane at 18h p.i. and remained in the inclusion membrane throughout the growth cycle. CPSIT_0844 and CPSIT_0846 could specifically be recognized by the antiserum of C. psittaci but failed to react with the antiserums of Chlamydia trachomatis and Chlamydia pneumoniae, which is consistent with the fact that they had no significant orthologs in C. trachomatis and C. pneumoniae. These results revealed that CPSIT_0844 and CPSIT_0846, the putative TMH family proteins, might be unique to C. psittaci and could be used to diagnose the infection caused by C. psittaci. Moreover, CPSIT_0844 and CPSIT_0846 could induce the expression of the inflammatory cytokines IL-1β, IL-6 and TNF-α in THP-1 cells, which might contribute to chlamydia-induced inflammatory pathologies.