Production of specific glycosidase activities by Streptococcus intermedius strain UNS35 grown in the presence of mucin.
An isolate of Streptococcus intermedius from a brain abscess showed neuraminidase (sialidase), beta-D-galactosidase, N-acetyl-beta-D-glucosaminidase and N-acetyl-beta-D-galactosaminidase activities. The optimal pH values of these enzymes were 5.5-6.0, 5.5-6.0, 5.0-5.5 and 5.0-5.5, respectively. The km of the enzymes varied according to whether the type of substrate was chromogenic or fluorogenic; sialidase was most active at the lowest substrate concentrations, with a km of 0.01 mM. In semi-defined medium, with porcine gastric mucin--a model glycoprotein--as the sole source of fermentable carbohydrate, levels of the glycosidases were significantly increased. Addition of glucose to the mucin-containing medium, or growth of cells in media supplemented with glucose alone, repressed glycosidic activities and the majority of these were cell-associated. S. intermedius cells from cultures grown with mucin were able, simultaneously, to transport via sugar:phosphoenolpyruvate phosphotransferase (PTS) systems, monosaccharides which are constituents of carbohydrate side chains of glycoproteins. These cells also possessed significant levels of neuraminate-pyruvate lyase, involved in the intracellular catabolism of neuraminic acid; this was absent from cells grown with glucose. These mechanisms, collectively, may facilitate the persistence and growth of S. intermedius in vivo.
Homer
K A
KA
Department of Dental Sciences, Faculty of Clinical Dentistry, King's College School of Medicine and Dentistry, Denmark Hill, London.
Whiley
R A
RA
Beighton
D
D
D001922:Brain Abscess / Q000382:microbiology; D004790:Enzyme Induction; D005947:Glucose / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000096:biosynthesis* / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009077:Mucins / Q000378:metabolism*; D007652:Oxo-Acid-Lyases / Q000378:metabolism; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism; D013290:Streptococcal Infections / Q000382:microbiology; D013291:Streptococcus / Q000201:enzymology*
D009077:Mucins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D006026:Glycoside Hydrolases; D007652:Oxo-Acid-Lyases; C018728:N-acetylneuraminate lyase; D005947:Glucose