title: Effect of mucin and glucose on proteolytic and glycosidic activities of Streptococcus oralis.
abstract: The production of glycosidase and protease activities, which may play a role in the degradation of human glycoproteins, by Streptococcus oralis strains isolated from endocarditis, septicaemia or the oral cavity was investigated with a range of fluorogenic substrates. The pH optima of the proteases ranged from 6.0 to 9.3 and the pH optima for the glycosidases were lower (4.5-6.0), although the pH range over which both groups of enzymes acted was broad. Growth in a minimal medium supplemented with glucose resulted in repression of glycosidase activities and elevated proteolytic activity. Bacteria from cultures supplemented with porcine gastric mucin (PGM), a model glycoprotein, exhibited higher levels of glycosidase activity, while proteolytic activity was suppressed and glycoprotein-derived monosaccharides were transported at significantly higher rates than those observed for cells grown in media with glucose. PGM-derived cells also exhibited high levels of N-acetylneuraminate pyruvate-lyase, the first intracellular enzyme in the pathway of sialic acid catabolism. Taken together, these data indicate that S. oralis strains produce a range of proteolytic and glycosidic enzymes that may play a role in the degradation of host-derived glycoproteins.
authors.affiliation: Department of Medical Microbiology, London Hospital Medical College, UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Rafay
authors.forename: K A
authors.initials: KA
authors.lastname: Homer
authors.forename: D
authors.initials: D
authors.lastname: Beighton
mesh_terms: D000595:Amino Acid Sequence; D016470:Bacteremia / Q000382:microbiology; D004697:Endocarditis, Bacterial / Q000382:microbiology; D010450:Endopeptidases / Q000378:metabolism*; D004790:Enzyme Induction; D005456:Fluorescent Dyes / Q000737:chemistry; D005947:Glucose / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009055:Mouth / Q000382:microbiology; D009077:Mucins / Q000378:metabolism*; D013290:Streptococcal Infections / Q000382:microbiology; D013291:Streptococcus / Q000201:enzymology*
chemical_list: D005456:Fluorescent Dyes; D006023:Glycoproteins; D009077:Mucins; D006026:Glycoside Hydrolases; D010450:Endopeptidases; D005947:Glucose