PMID:21078847

Citation	Duque, C, Stipp, RN, Wang, B, Smith, DJ, Höfling, JF, Kuramitsu, HK, Duncan, MJ and Mattos-Graner, RO (2011) Downregulation of GbpB, a component of the VicRK regulon, affects biofilm formation and cell surface characteristics of Streptococcus mutans. Infect. Immun. 79:786-96
Abstract	The virulence of the dental caries pathogen Streptococcus mutans relies in part on the sucrose-dependent synthesis of and interaction with glucan, a major component of the extracellular matrix of tooth biofilms. However, the mechanisms by which secreted and/or cell-associated glucan-binding proteins (Gbps) produced by S. mutans participate in biofilm growth remain to be elucidated. In this study, we further investigate GbpB, an essential immunodominant protein with similarity to murein hydrolases. A conditional knockdown mutant that expressed gbpB antisense RNA under the control of a tetracycline-inducible promoter was constructed in strain UA159 (UACA2) and used to investigate the effects of GbpB depletion on biofilm formation and cell surface-associated characteristics. Additionally, regulation of gbpB by the two-component system VicRK was investigated, and phenotypic analysis of a vicK mutant (UAvicK) was performed. GbpB was directly regulated by VicR, and several phenotypic changes were comparable between UACA2 and UAvicK, although differences between these strains existed. It was established that GbpB depletion impaired initial phases of sucrose-dependent biofilm formation, while exogenous native GbpB partially restored the biofilm phenotype. Several cellular traits were significantly affected by GbpB depletion, including altered cell shape, decreased autolysis, increased cell hydrophobicity, and sensitivity to antibiotics and osmotic and oxidative stresses. These data provide the first experimental evidence for GbpB participation in sucrose-dependent biofilm formation and in cell surface properties.
Links	PubMed PMC3028841 Online version:10.1128/IAI.00725-10
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Biofilms/growth & development; Down-Regulation; Gene Expression Regulation, Bacterial/physiology; Membrane Proteins/genetics; Membrane Proteins/metabolism; Mutation; RNA, Bacterial; Regulon/physiology; Streptococcus mutans/drug effects; Streptococcus mutans/genetics; Streptococcus mutans/metabolism; Streptococcus mutans/physiology; Sucrose/pharmacology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
STRMU:Q8DWM3		GO:0044011: single-species biofilm formation on inanimate substrate	ECO:0000315:		P		Fig. 4A/4B shows that biofilm formation on glass surfaces was impaired in GbpB knockdown mutants.	complete CACAO 7617
STRMU:Q8DWM3	involved_in	GO:0044011: single-species biofilm formation on inanimate substrate	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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