title: A galactose-specific sugar: phosphotransferase permease is prevalent in the non-core genome of Streptococcus mutans.
abstract: Three genes predicted to encode the A, B and C domains of a sugar : phosphotransferase system (PTS) permease specific for galactose\(EII(Gal) ) were identified in the genomes of 35 of 57 recently sequenced isolates of Streptococcus mutans, the primary etiological agent of human dental caries. Mutants defective in the EII(Gal) complex were constructed in six of the isolates and showed markedly reduced growth rates on galactose-based medium relative to the parental strains. An EII(Gal) -deficient strain constructed using the invasive serotype f strain OMZ175 (OMZ/IIGal) expressed significantly lower PTS activity when galactose was present as the substrate. Galactose was shown to be an effective inducer of catabolite repression in OMZ175, but not in the EII(Gal) -deficient strain. In a mixed-species competition assay with galactose as the sole carbohydrate source, OMZ/IIGal was less effective than the parental strain at competing with the oral commensal bacterium Streptococcus gordonii, which has a high-affinity galactose transporter. Hence, a significant proportion of S. mutans strains encode a galactose PTS permease that could enhance the ability of these isolates to compete more effectively with commensal streptococci for galactose in salivary constituents and the diet.
authors: Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA.
authors: L
authors: L
authors: Zeng
authors: P
authors: P
authors: Xue
authors: M J
authors: MJ
authors: Stanhope
authors: R A
authors: RA
authors: Burne
mesh_terms: D058491:Bacterial Load; D001431:Bacteriological Techniques; D057465:Catabolite Repression / Q000235:genetics; D018920:Coculture Techniques; D005690:Galactose / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D055786:Gene Knockout Techniques; D016680:Genome, Bacterial / Q000235:genetics; D006801:Humans; D056265:Microbial Interactions / Q000502:physiology; D009154:Mutation / Q000235:genetics; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics*; D012703:Serotyping; D054773:Streptococcus gordonii / Q000254:growth & development; D013295:Streptococcus mutans / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C038272:phosphoenolpyruvate-galactose phosphotransferase; D005690:Galactose
keywords: biofilm; dental caries; galactose-phosphotransferase system; sugar : phosphotransferase system; tagatose pathway