Insertional inactivation of the gene encoding a 76-kilodalton cell surface polypeptide in Streptococcus gordonii Challis has a pleiotropic effect on cell surface composition and properties

134

171

The highly conserved antigen I/II family of polypeptides produced by oral streptococci are believed to be colonization determinants and may mediate adhesion of bacterial cells to salivary glycoproteins absorbed to cells and tissues in the human oral cavity. Streptococcus gordonii is shown to express, on the cell surface, two antigen I/II polypeptides designated SspA and SspB (formerly Ssp-5) that are the products of tandemly arranged chromosomal genes. The structure and arrangement of these genes is similar in two independently isolated strains, DL1 and M5, of S. gordonii. The mature polypeptide sequences of M5 SspA (1539 amino acid (aa) residues) and SspB (1462 aa residues) are almost wholly conserved (98% identical) in the C-terminal regions (from residues 796 in SspA and 719 in SspB, to the respective C-termini), well-conserved (84%) at the N-terminal regions (residues 1-429), and divergent (only 27% identical residues) within the intervening central regions. Insertional inactivation of the sspA gene in S. gordonii DL1 resulted in reduced binding of cells to salivary agglutinin glycoprotein (SAG), human erythrocytes, and to the oral bacterium Actinomyces naeslundii. Further reductions in streptococcal cell adhesion to SAG and to two strains of A. naeslundii were observed when both sspA and sspB genes were inactivated. The results suggest that both SspA and SspB polypeptides are involved in adhesion of S. gordonii cells to human and bacterial receptors.

Section: Adhesion Assays and Elsamentioning

confidence: 99%

Tandem genes encode cell‐surface polypeptides SspA and SspB which mediate adhesion of the oral bacterium Streptococcus gordonii to human and bacterial receptors

Demuth

Duan

Brooks

et al. 1996

134

171

“…(1993), Proteins were separated by SDS-PAGE on 8% (w/v) gels and were stained with silver nitrate (Morrissey, 1981) or with Coomassie brilliant blue. Proteins were transferred from polyacrylamide gels to Hybond-C nitrocellulose membrane {Amersham) by eleclrobiotting in 25 mM Tris, 192 mM glycine, 20% (v/v) methanol (Towbin et al.-1979) at 20 V cm " ' for 90min, Immunoblots were incubated with antiserum diluted 1:500 and antibody binding was detected using peroxidase-conjugated swine immunoglobuiins to rabbit immunoglobulin G, as described by Jenkinson and Easingwood (1990).…”

Section: Analysis Of Bacterial Proteinsmentioning

confidence: 99%

“…In Streptococcus gordonii, several cell-surface poiypeptides have been identified that appear to be involved in adhesion and colonization. SarA (76 kDa) in S. gordonii DL1 is a lipoprotein (Jeni<inson, 1992) involved in determining cell-aggregation properties, in particular with oral Actinomyces (Jenkinson and Easingwood, 1990). ScaA (38 kDa) in S. gordonii PK488 is aiso a iipoprotein (Andersen et ai, 1993) and is associated with the coaggregation of S. gordonii with Actinomyces naeslundii.…”

Section: Introductionmentioning

confidence: 99%

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

McNab

Jenkinson

Loach

et al. 1994

105

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.

“…Several cell surface proteins have been implicated in adherence, hydrophobicity and aggregation reactions in S, gordonii (Jenkinson, 1986;1987;Jenkinson and Easingwood, 1990). Mutants with either reduced or increased cell-surface hydrophobicity were isolated following ethylmethane sulphonate mutagenesis of S. gordonii (Jenkinson and Carter, 1988).…”

Section: Introductionmentioning

confidence: 99%

Gene disruption identifies a 290 kDa cell‐surface polypeptide conferring hydrophobicity and coaggregation properties in Streptococcus gordonii

McNab

Jenkinson

1992

The C-terminal coding region of the gene (denoted cshA) encoding a high-molecular-mass (290 kDa) cell-surface polypeptide in the oral bacterium Streptococcus gordonii was cloned and sequenced. Insertion of ermAM into the S. gordonii chromosome at the 3' end of the coding region of cshA led to the production of isogenic mutants that secreted a truncated form (260 kDa) of the CshA polypeptide into the growth medium. Mutants had reduced cell-surface hydrophobicity and were impaired in their ability to coaggregate with oral actinomyces. The results identify a carboxyl terminus-anchored cell-surface protein determinant of hydrophobicity and coaggregation in S. gordonii.