Inactivation of the gene encoding surface protein SspA in Streptococcus gordonii DL1 affects cell interactions with human salivary agglutinin and oral actinomyces

Abstract

Chem. 265:7120-7126, 1990).The region of the gene encoding an N-terminal segment of a related polypeptide (SspA) in S. gordonii DL1 (Challis) was isolated following polymerase chain reaction amplification of genomic DNA. The sspA gene in S. gordonii DL1 was insertionally inactivated by homologous recombination of the erythromycin resistance (Emr) determinant ermAM onto the streptococcal chromosome. The SspA polypeptide (apparent molecular mass, 210 kDa) was detected on Western blots (immunoblots) of spheroplast extracts and extracellular culture medium proteins from wild-type strain DL1 but was absent from Emr mutants. One SspAmutant (designated OB220) was not altered in rate or extent of aggregation by whole saliva or parotid saliva but showed reduced aggregation in the presence of purified salivary agglutinin. Mutant bacteria were unaffected in their ability to adhere to hydroxylapatite beads coated with whole or parotid saliva and were unaltered in cell surface hydrophobicity. However, the SspAstrain OB220 was deficient in binding salivary agglutinin and in binding to six strains of Actinomyces naeslhdii. Therefore, expression of SspA polypeptide in S. gordonii is associated with both agglutinin-dependent and agglutinin-independent aggregation and adherence reactions of streptococcal cells.

Binding ofStreptococcus gordoniito extracellular matrix proteins

“…Detailed information on size and position of deletions and insertions in S. gordonii mutants is given in Table 1. Inactivated genes included gtfG, encoding the single glucosyltransferase of S. gordonii Challis (Grahame & Mayer, 1985;Haisman & Jenkinson, 1991;Vacca-Smith et al, 1994;Vickerman et al, 1996), hsa, encoding a sialic acid-binding adhesin (Takahashi et al, 2002), cshA and fbpA, encoding two fibronectin-binding adhesins (McNab & Jenkinson, 1992;McNab et al, 1996;Christie et al, 2002), sspA and sspB, encoding adhesins that bind to salivary glycoproteins, collagen and other oral microorganisms (Jenkinson et al, 1993;Demuth et al, 1996), msrA, which encodes for a methionine sulfoxide reductase believed to be involved in stabilization of bacterial adhesins (Wizemann et al, 1996;Vriesema et al, 2000), and the RPS locus, responsible for the biosynthesis of the cell wall polysaccharide (Xu et al, 2003). Although these S. gordonii surface proteins have been characterized and analyzed for their function in previous studies, including those cited above, no study has been reported, that systematically analyzes many different mutants of the same strain for binding to EMPs.…”

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

“…Human salivary 7-amylase binding was measured as described by Douglas (1990). Adherence of streptococci to Actinomyces immobilized in the wells of microtitre plates was measured as described by Jenkinson et al (1993), Human tissue proteins were applied to the wells of microtitre plates (1 to 5ng per well) and adherence of radioactively labelled streptococci was determined as previously reported (Jenkinson ef ai, 1993). Colonization studies employing Streptococcus-and Lactobaciilus-ivQe mice were performed as described by Loach etal.…”

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

“…This bacterium has a vast repertoire of adherence properties and is able to bind a range of salivary components (reviewed by Jenkinson, 1995). The S. gordonii antigen 1/ 11 polypeptides desig-agglutinin glycoprotein (Demuth et a/., 1989;1990a;Jenkinson et a/., 1993), a reaction that is inhibited by sialic acid (Demuth eta/., 1990a). In addition, the SspA polypeptide has been shown to be involved in binding of streptococci to Actinomyces naeslundii (Jenkinson et a/., 1993), an organism found closely associated with S. gordonii and Streptococcus oralis in dental plaque (Kolenbrander and London, 1993).…”