Identification of Anion Channels Responsible for Fluoride Resistance in Oral Streptococci

• Published in: PLOS ONE Vol. 11; no. 11; p. e0165900
• Main Authors: Men, Xiaochen, Shibata, Yukie, Takeshita, Toru, Yamashita, Yoshihisa
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science (PLoS) 08.11.2016; Public Library of Science
• Subjects: Anion channels; Bacteria; Biofilms; Biology and Life Sciences; Blast resistance; Chloride; Cloning; Coexistence; Complementation; Dentistry; Deoxyribonucleic acid; DNA; Drug Resistance, Bacterial; Drug Resistance, Bacterial - genetics; E coli; Escherichia coli; Fluorides; Fluorides - pharmacology; Genes; Genes, Bacterial; Genes, Bacterial - genetics; Genetic engineering; Genomes; Humans; Ion Channels; Ion Channels - genetics; Ion Channels - physiology; Laboratories; Medicine; Medicine and Health Sciences; Mens health; Metabolism; Mouth; Mouth - microbiology; Oral hygiene; Physical Sciences; Plasmids; Public health; Q; R; Relative abundance; Research and Analysis Methods; Research Article; Science; Streptococcus; Streptococcus - drug effects; Streptococcus - genetics; Streptococcus anginosus; Streptococcus anginosus - drug effects; Streptococcus anginosus - genetics; Streptococcus gordonii; Streptococcus gordonii - drug effects; Streptococcus gordonii - genetics; Streptococcus infections; Streptococcus intermedius; Streptococcus intermedius - drug effects; Streptococcus intermedius - genetics; Streptococcus mitis; Streptococcus mutans; Streptococcus mutans - drug effects; Streptococcus mutans - genetics; Streptococcus oralis; Streptococcus oralis - drug effects; Streptococcus oralis - genetics; Streptococcus salivarius; Streptococcus salivarius - drug effects; Streptococcus salivarius - genetics; Streptococcus sanguinis; Streptococcus sobrinus; Streptococcus sobrinus - drug effects; Streptococcus sobrinus - genetics; Toxicity
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0165900

Recently, it has been reported that eriC and crcB are involved in bacterial fluoride resistance. However, the fluoride-resistance mechanism in oral streptococci remains unclear. BLAST studies showed that two types of eriCs (eriC1 and eriC2) and two types of crcBs (crcB1 and crcB2) are present across 18 oral streptococci, which were identified in ≥ 10% of 166 orally healthy subjects with ≥ 0.01% of the mean relative abundance. They were divided into three groups based on the distribution of these four genes: group I, only eriC1; group II, eriC1 and eriC2; and group III, eriC2, crcB1, and crcB2. Group I consisted of Streptococcus mutans, in which one of the two eriC1s predominantly affected fluoride resistance. Group II consisted of eight species, and eriC1 was responsible for fluoride resistance, but eriC2 was not, in Streptococcus anginosus as a representative species. Group III consisted of nine species, and both crcB1 and crcB2 were crucial for fluoride resistance, but eriC2 was not, in Streptococcus sanguinis as a representative species. Based on these results, either EriC1 or CrcBs play a role in fluoride resistance in oral streptococci. Complementation between S. mutans EriC1 and S. sanguinis CrcB1/CrcB2 was confirmed in both S. mutans and S. sanguinis. However, neither transfer of S. sanguinis CrcB1/CrcB2 into wild-type S. mutans nor S. mutans EriC1 into wild-type S. sanguinis increased the fluoride resistance of the wild-type strain. Co-existence of different F- channels (EriC and CrcB) did not cause the additive effect on fluoride resistance in oral Streptococcus species.