title: Inhibition of the synthesis and secretion of extracellular glucosyl- and fructosyltransferase in Streptococcus sanguis by sodium ions.
abstract: The influence of Na+ and K+ on the synthesis and secretion of extracellular glucosyltransferase (GTF; EC 2.4.1.5) and fructosyltransferase (FTF; EC 2.4.1.10) by Streptococcus sanguis NCTC 7865 and Streptococcus sanguis Challis NCTC 7868 has been determined. No FTF and little or no mutansucrase (GTF-I) activities were detectable during growth on glucose or sucrose unless the Na+/K+ ratio of the cultures was kept low. Increasing K+ concentrations stimulated the production of FTF and dextransucrase (GTF-S), but all glycosyltransferase activities decreased in high K+ media when the growth pH was maintained with NaOH instead of KOH, indicating that the Na+/K+ ratio effect was due principally to Na+ inhibition. Significant GTF and FTF activities were detected in a putative GTF- mutant of strain Challis grown in high K+ medium but not in high Na+ medium, suggesting that the mutant might be defective in a regulatory gene.
mesh_terms: D003470:Culture Media; D005964:Glucosyltransferases / Q000096:biosynthesis* / Q000378:metabolism; D006602:Hexosyltransferases / Q000096:biosynthesis* / Q000378:metabolism; D009154:Mutation; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology*; D013298:Streptococcus sanguis / Q000187:drug effects / Q000201:enzymology*; D001426:Bacterial Proteins
chemical_list: D003470:Culture Media; D005964:Glucosyltransferases; D006602:Hexosyltransferases; D011188:Potassium; D012964:Sodium; C021451:inulosucrase; D001426:Bacterial Proteins