title: Characterization of the dextran-binding domain in the glucan-binding protein C of Streptococcus mutans.
abstract: OBJECTIVE
  Streptococcus mutans produces multiple glucan-binding proteins (Gbps), among which GbpC encoded by the gbpC gene is known to be a cell-surface-associated protein involved in dextran-induced aggregation. The purpose of the present study was to characterize the dextran-binding domain of GbpC using bioinformatics analysis and molecular techniques.
  
  
  RESULTS
  Bioinformatics analysis specified five possible regions containing molecular binding sites termed GB1 through GB5. Next, truncated recombinant GbpC (rGbpC) encoding each region was produced using a protein expression vector and five deletion mutant strains were generated, termed CDGB1 through CDGB5 respectively. The dextran-binding rates of truncated rGbpC that included the GB1, GB3, GB4 and GB5 regions in the upstream sequences were higher than that of the construct containing GB2 in the downstream region. In addition, the rates of dextran-binding for strains CDGB4 and CD1, which was entire gbpC deletion mutant, were significantly lower than for the other strains, while those of all other deletion mutants were quite similar to that of the parental strain MT8148. Biofilm structures formed by CDGB4 and CD1 were not as pronounced as that of MT8148, while those formed by other strains had greater density as compared to that of CD1.
  
  
  CONCLUSIONS
  Our results suggest that the dextran-binding domain may be located in the GB4 region in the interior of the gbpC gene.
  
  
  CONCLUSIONS
  Bioinformatics analysis is useful for determination of functional domains in many bacterial species.
authors.affiliation: Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takashima
authors.affiliation: Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: A C
authors.initials: AC
authors.lastname: Ardin
authors.affiliation: Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nagayama
authors.affiliation: Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Nomura
authors.affiliation: Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nakano
authors.affiliation: Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Matsumoto-Nakano
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003911:Dextrans / Q000378:metabolism*; D037102:Lectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D013295:Streptococcus mutans / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D003911:Dextrans; D037102:Lectins; C037937:glucan-binding proteins
keywords: Streptococcus mutans; biofilm; bioinformatics; dextran-binding domain; glucan-binding protein C