Cell‐surface‐associated polypeptides CshA and CshB of high molecular mass are colonization determinants in the oral bacterium Streptococcus gordonii

Abstract

The human oral bacterium Streptococcus gordonii expresses, on the cell surface, two antigenically related high-molecular-mass polypeptides denoted CshA and CshB, encoded by genes at separate chromosomal loci. The precursor form of CshA is composed of four distinct segments: (i) a 41-amino-acid residue leader peptide, (ii) N-terminal 42-878 residues, (iii) residues 879-2417 comprising 13 repeat blocks of 101 amino acid residues and three shorter blocks, and (iv) a C-terminal anchor domain similar to those present in some other Gram-positive bacterial cell-wall polypeptides. Insertional mutations within cshA reduced both cell-surface hydrophobicity and ability to adhere to oral Actinomyces naeslundii. Insertional mutations in cshB had less effect on hydrophobicity and coadherence. However, expression of both polypeptides was found to be necessary for streptococci to colonize the murine oral cavity.

Expression of fibronectin-binding protein FbpA modulates adhesion in Streptococcus gordonii The GenBank accession number for the sequence reported in this paper is X65164.

“…In this study, we have identified FbpA as a second fibronectin-binding protein in oral S. gordonii. The fbpA gene lies immediately downstream of the cshA gene that encodes a major fibronectin-binding protein of S. gordonii (McNab et al, 1994(McNab et al, , 1996.…”

“…Plasmid pPH1704 contained a 2n2 kb S. gordonii DNA fragment, 1n5 kb of which has been shown to encode the carboxy terminus of CshA (McNab & Jenkinson, 1992). The sequence of the remaining 0n7 kb of the S. gordonii DNA fragment was determined and used to design primers for inverse PCR amplification of flanking DNA (McNab et al, 1994). Briefly, S. gordonii DL1 genomic DNA was digested with SspI, selfligated at 3n5 ng µl − " and then used as a template for PCR (Expand High Fidelity System ; Boehringer Mannheim) with the primers CTERM (5h-TTATACAGGACAGAAAACCC3h ; complementary to nucleotides 8298-8317, cshA locus ; GenBank accession no.…”

Adhesion of Candida albicans to oral streptococci is promoted by selective adsorption of salivary proteins to the streptococcal cell surface

“…C. albicans ATCC 10261 was the yeast strain used in this study. Streptococcal cells were grown on TSBY agar (l − " : 20 g trypticase soy broth, 5 g yeast nitrogen broth, 5 g glucose, 20 g agar) or in BHY (l − " : 37 g brain heart infusion, 5 g yeast extract) medium at 37 mC in screw-capped tubes or bottles as stationary cultures (McNab et al, 1994). Late-exponential-phase cultures (OD '!!…”

Polypeptides associated with tufts of cell-surface fibrils in an oral Streptococcus

“…This has also been shown recently for isogenic mutants of S. gordonii deficient in production of surface polypeptides CshA and CshB. These mutants had much-reduced cell-surface hydrophobicity but nevertheless adhered normally to experimental salivary pellicles (McNab et al, 1994). In summary, adhesion of strain CN3410 cells to parotid salivary pellicle is not sensitive to trypsin under the conditions employed, is independent of cell-surface hydrophobicity, and does not involve the long or short components of the fibril tufts since these were wholly removed by trypsin treatment of cells.…”