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This Article Full Text (Papers in Press[PDF]) All Versions of this Article: mic.0.027854-0v1 155/6/1977    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Davies, J. R. Articles by Herzberg, M. C. Search for Related Content PubMed PubMed Citation Articles by Davies, J. R. Articles by Herzberg, M. C. Agricola Articles by Davies, J. R. Articles by Herzberg, M. C.

Identification of novel LPXTG-linked surface proteins from Streptococcus gordonii

¹ Malmo University;
² University of Minnesota

ABSTRACT

Surface adhesion plays an essential part in the survival of the commensal organism Streptococcus gordonii in the oral cavity as well as during opportunistic infections such as endocarditis. At least two types of cell surface protein involved in adhesion are found on the surface of Gram-positive bacteria: those anchored via an LPXTG motif by the enzyme sortase A (srtA) and those associated with the cell surface by, as yet, unknown mechanisms. In srtA- mutants, LPXTG-containing proteins have been shown to be released rather than cross-linked to the cell wall. We have therefore used two-dimensional gel electrophoresis of released proteins from a srtA- mutant as well as the wild type strain, followed by peptide identification with mass spectrometry to identify a set of novel proteins predicted to be present on the surface of S. gordonii DL1. This includes two large LPXTG-linked proteins (SGO_0707 and SGO_1487) which both contain tandemly-repeated sequences similar to those present in known fibrillar adhesins. A 5'-nucleotidase and a protein with a putative collagen-binding domain, both containing LPXTG motifs, were also identified. Anchorless proteins with known chaperone, stress response and elongation factor functions, apparently responsible for bacterial binding to keratinocytes and saliva coated surfaces in the absence of the LPXTG-linked adhesins, were also associated with the cell surface. These data reveal a range of proteins to be present on the S. gordonii DL1 cell surface, whose expression plays an important role in adhesion to epithelia and which represent likely candidates for novel virulence factors in S. gordonii.

³ E-mail: julia.davies{at}mah.se