title: Xylitol disturbs protein synthesis, including the expression of HSP-70 and HSP-60, in Streptococcus mutans.
abstract: Xylitol, a natural sugar alcohol and a caries-preventive carbohydrate sweetener, inhibits xylitol-sensitive wild-type Streptococcus mutans but also selects for its natural xylitol-resistant mutants. The aim of the work was to verify the influence of xylitol on heat shock proteins HSP-60 (GroEL-like) and HSP-70 (DnaK-like) in xylitol-sensitive and xylitol-resistant strains. Cells from fresh isolate S. mutans 123.1 were grown at 37 degrees C and constant pH 7.0. The cell culture was stressed by raising the temperature to 43 degrees C or adding xylitol (4% final). Cell proteins labeled with a cocktail of 14C-amino acids were analyzed by SDS-PAGE and autoradiography whereas HSP-60 and HSP-70 were visualized using Western immunoblotting. In both xylitol-sensitive and xylitol-resistant strains, heat stress was associated with an increase of both HSP-60 (63 kDa) and HSP-70 (71 kDa) and a decrease in the intensity of a number of other protein bands compared with cells maintained at 37 degrees C. Exposure to xylitol but not to other polyols induced a decrease of both these heat shock proteins in the xylitol-sensitive strain but did not modify them in the xylitol-resistant mutant. It also decreased all protein bands above 60 kDa together with a 53 kDa protein and increased the amount of 57-, 50- and 40-kDa proteins in the xylitol-sensitive strain whereas the proteins of the xylitol-resistant strain remained unchanged. The results suggest that xylitol is a strong metabolic inhibitor that disturbs protein synthesis and reduces the expression of HSP-70 and HSP-60 proteins in the wild-type xylitol-sensitive S. mutans but not in the xylitol-resistant natural mutant strain.
authors.affiliation: Groupe de Recherche en Ecologie Buccale, Faculté de médecine dentaire, Université Laval, Québec, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Hrimech
authors.forename: D
authors.initials: D
authors.lastname: Mayrand
authors.forename: D
authors.initials: D
authors.lastname: Grenier
authors.forename: L
authors.initials: L
authors.lastname: Trahan
mesh_terms: D001345:Autoradiography; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis*; D015153:Blotting, Western; D018834:Chaperonin 60 / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D004352:Drug Resistance, Microbial; D004591:Electrophoresis, Polyacrylamide Gel; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D006863:Hydrogen-Ion Concentration; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects* / Q000378:metabolism; D014993:Xylitol / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D018834:Chaperonin 60; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D011500:Protein Synthesis Inhibitors; C063842:dnaK protein, E coli; D014993:Xylitol