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Open Access Research article

Comprehensive in silico prediction and analysis of chlamydial outer membrane proteins reflects evolution and life style of the Chlamydiae

Eva Heinz1, Patrick Tischler3, Thomas Rattei23, Garry Myers4, Michael Wagner1 and Matthias Horn1*

Author Affiliations

1 Department of Microbial Ecology, Faculty of Life Sciences, University of Vienna, Vienna, Austria

2 Department of Computational Systems Biology, Faculty of Life Sciences, University of Vienna, Vienna, Austria

3 Genome oriented Bioinformatics, Technische Universität München, Freising, Germany

4 Institute for Genome Science, University of Maryland, Baltimore, MD, USA

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BMC Genomics 2009, 10:634  doi:10.1186/1471-2164-10-634

Published: 29 December 2009

Abstract

Background

Chlamydiae are obligate intracellular bacteria comprising some of the most important bacterial pathogens of animals and humans. Although chlamydial outer membrane proteins play a key role for attachment to and entry into host cells, only few have been described so far. We developed a comprehensive, multiphasic in silico approach, including the calculation of clusters of orthologues, to predict outer membrane proteins using conservative criteria. We tested this approach using Escherichia coli (positive control) and Bacillus subtilis (negative control), and applied it to five chlamydial species; Chlamydia trachomatis, Chlamydia muridarum, Chlamydia (a.k.a. Chlamydophila) pneumoniae, Chlamydia (a.k.a. Chlamydophila) caviae, and Protochlamydia amoebophila.

Results

In total, 312 chlamydial outer membrane proteins and lipoproteins in 88 orthologous clusters were identified, including 238 proteins not previously recognized to be located in the outer membrane. Analysis of their taxonomic distribution revealed an evolutionary conservation among Chlamydiae, Verrucomicrobia, Lentisphaerae and Planctomycetes as well as lifestyle-dependent conservation of the chlamydial outer membrane protein composition.

Conclusion

This analysis suggested a correlation between the outer membrane protein composition and the host range of chlamydiae and revealed a common set of outer membrane proteins shared by these intracellular bacteria. The collection of predicted chlamydial outer membrane proteins is available at the online database pCOMP http://www.microbial-ecology.net/pcomp webcite and might provide future guidance in the quest for anti-chlamydial vaccines.