Open AccessFunctional Analysis of Glucan Binding Protein B from Streptococcus mutans
Author(s) -
Renata O. Mattos-Graner,
Kristen A. Porter,
Daniel J. Smith,
Yumiko Hosogi,
Marilyn J. Duncan
Publication year - 2006
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.01845-05
Subject(s) - biology , peptidoglycan , streptococcus mutans , mutant , ribosomal protein , gene , microbiology and biotechnology , gene expression , genetics , biochemistry , bacteria , rna , ribosome
Mutans streptococci are major etiological agents of dental caries, and several of their secreted products contribute to bacterial accumulation on teeth. Of these,Streptococcus mutans glucan binding protein B (GbpB) is a novel, immunologically dominant protein. Its biological function is unclear, although GbpB shares homology with a putative peptidoglycan hydrolase fromS. agalactiae andS. pneumoniae , indicative of a role in murein biosynthesis. To determine the cellular function of GbpB, we used several approaches to inactivate the gene, analyze its expression, and identify interacting proteins. None of the transformants analyzed were truegbpB mutants, since they all contained both disrupted and wild-type gene copies, and expression of functional GbpB was always conserved. Thus, the inability to obtain viablegbpB null mutants supports the notion thatgbpB is an essential gene. Northern blot and real-time PCR analyses suggested that induction ofgbpB expression in response to stress was a strain-dependent phenomenon. Proteins that interacted with GbpB were identified in pull-down and coimmunoprecipitation assays, and these data suggest that GbpB interacts with ribosomal protein L7/L12, possibly as part of a protein complex involved in peptidoglycan synthesis and cell division.