Multi-genome identification and characterization of chlamydiae-specific type III secretion substrates: the Inc proteins

BMC Genomics

Research Article

Guangming Zhong¹  Rhonda Flores¹  Pierre Dehoux²  Catherine Dauga²  Agathe Subtil³ 

[1] Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, 78229, San Antonio, TX, USA;Institut Pasteur, Génopôle, Plate-forme Intégration et Analyse génomique, Paris, France;Institut Pasteur, Unité de Biologie des Interactions Cellulaires, Paris, France;CNRS URA, 2582, Paris, France;

关键词: Transmembrane Segment;    Coiled Coil;    Hydrophobic Domain;    Inclusion Membrane;    Secretion Assay;   

DOI  :  10.1186/1471-2164-12-109

 received in 2010-07-16, accepted in 2011-02-16,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundChlamydiae are obligate intracellular bacteria that multiply in a vacuolar compartment, the inclusion. Several chlamydial proteins containing a bilobal hydrophobic domain are translocated by a type III secretion (TTS) mechanism into the inclusion membrane. They form the family of Inc proteins, which is specific to this phylum. Based on their localization, Inc proteins likely play important roles in the interactions between the microbe and the host. In this paper we sought to identify and analyze, using bioinformatics tools, all putative Inc proteins in published chlamydial genomes, including an environmental species.ResultsInc proteins contain at least one bilobal hydrophobic domain made of two transmembrane helices separated by a loop of less than 30 amino acids. Using bioinformatics tools we identified 537 putative Inc proteins across seven chlamydial proteomes. The amino-terminal segment of the putative Inc proteins was recognized as a functional TTS signal in 90% of the C. trachomatis and C. pneumoniae sequences tested, validating the data obtained in silico. We identified a macro domain in several putative Inc proteins, and observed that Inc proteins are enriched in segments predicted to form coiled coils. A surprisingly large proportion of the putative Inc proteins are not constitutively translocated to the inclusion membrane in culture conditions.ConclusionsThe Inc proteins represent 7 to 10% of each proteome and show a great degree of sequence diversity between species. The abundance of segments with a high probability for coiled coil conformation in Inc proteins support the hypothesis that they interact with host proteins. While the large majority of Inc proteins possess a functional TTS signal, less than half may be constitutively translocated to the inclusion surface in some species. This suggests the novel finding that translocation of Inc proteins may be regulated by as-yet undetermined mechanisms.

【 授权许可】

Unknown   
© Dehoux et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.