title: Contribution of chloride channel permease to fluoride resistance in Streptococcus mutans.
abstract: Genes encoding fluoride transporters have been identified in bacterial and archaeal species. The genome sequence of the cariogenic Streptococcus mutans bacteria suggests the presence of a putative fluoride transporter, which is referred to as a chloride channel permease. Two homologues of this gene (GenBank locus tags SMU_1290c and SMU_1289c) reside in tandem in the genome of S. mutans The aim of this study was to determine whether the chloride channel permeases contribute to fluoride resistance. We constructed SMU_1290c- and SMU_1289c-knockout S. mutans UA159 strains. We also constructed a double-knockout strain lacking both genes. SMU_1290c or SMU_1289c was transformed into a fluoride transporter- disrupted Escherichia coli strain. All bacterial strains were cultured under appropriate conditions with or without sodium fluoride, and fluoride resistance was evaluated. All three gene-knockout S. mutans strains showed lower resistance to sodium fluoride than did the wild-type strain. No significant changes in resistance to other sodium halides were recognized between the wild-type and double-knockout strains. Both SMU_1290c and SMU_1289c transformation rescued fluoride transporter-disrupted E. coli cell from fluoride toxicity. We conclude that the chloride channel permeases contribute to fluoride resistance in S. mutans.
authors.affiliation: Department of Translational Research, Tsurumi University School of Dental Medicine, Yokohama 230-8501, Japan murata-ta@tsurumi-u.ac.jp.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Murata
authors.affiliation: Department of Translational Research, Tsurumi University School of Dental Medicine, Yokohama 230-8501, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Hanada
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D055786:Gene Knockout Techniques; D016680:Genome, Bacterial; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D012964:Sodium / Q000737:chemistry / Q000494:pharmacology; D012969:Sodium Fluoride / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development
chemical_list: D001426:Bacterial Proteins; D018118:Chloride Channels; D026901:Membrane Transport Proteins; D012969:Sodium Fluoride; D012964:Sodium
keywords: SMU_1289c; SMU_1290c; Streptococcus mutans; chloride channel permease; fluoride