Streptococcus mutans: fructose transport, xylitol resistance, and virulence.
Streptococcus mutans, the primary etiological agent of human dental caries, possesses at least two fructose phosphotransferase systems (PTSs), encoded by fruI and fruCD. fruI is also responsible for xylitol transport. We hypothesized that fructose and xylitol transport systems do not affect virulence. Thus, colonization and cariogenicity of fruI(-) and fruCD(-) single and double mutants, their WT (UA159), and xylitol resistance (X(r)) of S. mutans were studied in rats fed a high-sucrose diet. A sucrose phosphorylase (gtfA(-)) mutant and a reference strain (NCTC-10449S) were additional controls. Recoveries of fruI mutant from the teeth were decreased, unlike those for the other strains. The fruCD mutation was associated with a slight loss of cariogenicity on enamel, whereas mutation of fruI was associated with a loss of cariogenicity in dentin. These results also suggest why xylitol inhibition of caries is paradoxically associated with spontaneous emergence of so-called X(r) S. mutans in habitual human xylitol users.
University of Connecticut, School of Dental Medicine, Farmington, CT 06030-1605, USA. Tanzer@nso.uchc.edu
J M
JM
Tanzer
A
A
Thompson
Z T
ZT
Wen
R A
RA
Burne
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001693:Biological Transport, Active; D015169:Colony Count, Microbial; D003731:Dental Caries / Q000382:microbiology / Q000517:prevention & control*; D003743:Dental Enamel / Q000473:pathology; D003804:Dentin / Q000473:pathology; D004037:Diet, Cariogenic; D005632:Fructose / Q000378:metabolism*; D017353:Gene Deletion; D005798:Genes, Bacterial; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D013045:Species Specificity; D013295:Streptococcus mutans / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism; D014993:Xylitol / Q000378:metabolism* / Q000627:therapeutic use
D001426:Bacterial Proteins; D037521:Virulence Factors; D005632:Fructose; D005964:Glucosyltransferases; C025901:sucrose phosphorylase; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D014993:Xylitol