Biological functions of glucan-binding protein B of Streptococcus mutans.
BACKGROUND
Streptococcus mutans has been implicated as a major causative agent of dental caries in humans. Bacterial components associated with the adhesion phase of S. mutans include glucosyltransferases, protein antigen C and proteins that bind glucan. At least four glucan-binding proteins (Gbp) have been identified; GbpA, GbpB, GbpC and GbpD.


METHODS
In our previous study, the contributions of GbpA and GbpC to the virulence of S. mutans were investigated; however, the biological function of GbpB and its role in the virulence of S. mutans remain to be elucidated. Using a GbpB-deficient mutant strain (BD1), we demonstrated in the present study that GbpB has a role in the biology of S. mutans.


RESULTS
The growth rate of BD1 was lower than that of other strains, while it was also shown to be less susceptible to phagocytosis and to form longer chains than the parental strain MT8148. In addition, electron microscope observations of the cell surfaces of BD1 showed that the cell-wall layers were obscure.


CONCLUSIONS
These results suggest that GbpB may have an important role in cell-wall construction and be involved in cell separation and cell maintenance.
Fujita
K
K
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Osaka, Japan.
Matsumoto-Nakano
M
M
Inagaki
S
S
Ooshima
T
T
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000942:Antigens, Bacterial / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D002473:Cell Wall / Q000648:ultrastructure; D006023:Glycoproteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D037102:Lectins / Q000235:genetics / Q000502:physiology; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D009154:Mutation / Q000235:genetics; D009504:Neutrophils / Q000502:physiology; D010587:Phagocytosis / Q000502:physiology; D013295:Streptococcus mutans / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D014774:Virulence