Open Access Research article

Complete genome and comparative analysis of Streptococcus gallolyticus subsp. gallolyticus, an emerging pathogen of infective endocarditis

Dennis Hinse1, Tanja Vollmer1, Christian Rückert2, Jochen Blom3, Jörn Kalinowski2, Cornelius Knabbe1 and Jens Dreier1*

Author Affiliations

1 Institut für Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum Nordrhein-Westfalen, Universitätsklinik der Ruhr-Universität Bochum, Georgstraße 11, 32545 Bad Oeynhausen, Germany

2 Institute for Genome Research and Systems Biology, Center for Biotechnology, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany

3 Bioinformatics Resource Facility, Center for Biotechnology, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany

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BMC Genomics 2011, 12:400  doi:10.1186/1471-2164-12-400

Published: 8 August 2011

Abstract

Background

Streptococcus gallolyticus subsp. gallolyticus is an important causative agent of infectious endocarditis, while the pathogenicity of this species is widely unclear. To gain insight into the pathomechanisms and the underlying genetic elements for lateral gene transfer, we sequenced the entire genome of this pathogen.

Results

We sequenced the whole genome of S. gallolyticus subsp. gallolyticus strain ATCC BAA-2069, consisting of a 2,356,444 bp circular DNA molecule with a G+C-content of 37.65% and a novel 20,765 bp plasmid designated as pSGG1. Bioinformatic analysis predicted 2,309 ORFs and the presence of 80 tRNAs and 21 rRNAs in the chromosome. Furthermore, 21 ORFs were detected on the plasmid pSGG1, including tetracycline resistance genes telL and tet(O/W/32/O). Screening of 41 S. gallolyticus subsp. gallolyticus isolates revealed one plasmid (pSGG2) homologous to pSGG1. We further predicted 21 surface proteins containing the cell wall-sorting motif LPxTG, which were shown to play a functional role in the adhesion of bacteria to host cells. In addition, we performed a whole genome comparison to the recently sequenced S. gallolyticus subsp. gallolyticus strain UCN34, revealing significant differences.

Conclusions

The analysis of the whole genome sequence of S. gallolyticus subsp. gallolyticus promotes understanding of genetic factors concerning the pathogenesis and adhesion to ECM of this pathogen. For the first time we detected the presence of the mobilizable pSGG1 plasmid, which may play a functional role in lateral gene transfer and promote a selective advantage due to a tetracycline resistance.