title: The adaptive response of Streptococcus mutans towards oral care products: involvement of the ClpP serine protease.
abstract: In the oral cavity a balanced physiological response is essential for Streptococcus mutans to survive various types of external challenges. In this study we examined the role of the ClpP serine protease in the response of S. mutans towards sodium fluoride, sodium chloride, hydrogen peroxide, and chlorhexidine. By constructing a clpP promoter-green fluorescent protein reporter strain, we showed increased fluorescence intensities under all types of stress, indicating a need for ClpP under all these challenges. We constructed a clpP knockout mutant, which proved to be more sensitive to all the challenges than the wild-type strain. This knockout strain also displayed a reduced growth rate, hyperaggregation, and increased biofilm formation. Furthermore, an increased resistance to toxic levels of hydrogen peroxide and chlorhexidine after pre-incubation with sublethal levels of the corresponding compounds was found in the wild-type strain but not in the knockout mutant. In conclusion, ClpP is involved in the general stress response of S. mutans and assists the bacteria to resist killing through adaptation.
authors.affiliation: Department of Cariology Endodontology Pedodontology, Academic Center for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands. d.deng@acta.nl
authors.forename: Dong Mei
authors.initials: DM
authors.lastname: Deng
authors.forename: Jacob M
authors.initials: JM
authors.lastname: ten Cate
authors.forename: Wim
authors.initials: W
authors.lastname: Crielaard
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics / Q000502:physiology; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development; D002710:Chlorhexidine / Q000494:pharmacology; D049071:Endopeptidase Clp / Q000235:genetics / Q000502:physiology*; D004790:Enzyme Induction; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D006360:Heat-Shock Proteins / Q000235:genetics / Q000502:physiology; D018869:Heat-Shock Response / Q000235:genetics / Q000502:physiology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology; D012969:Sodium Fluoride / Q000494:pharmacology; D013295:Streptococcus mutans / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
chemical_list: D000891:Anti-Infective Agents, Local; D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D049452:Green Fluorescent Proteins; D012965:Sodium Chloride; D012969:Sodium Fluoride; D006861:Hydrogen Peroxide; D049071:Endopeptidase Clp; D002710:Chlorhexidine