Identification of Anion Channels Responsible for Fluoride Resistance in Oral Streptococci.
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.
Section of Preventive and Public Health Dentistry, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
Xiaochen
X
Men
Section of Preventive and Public Health Dentistry, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
Yukie
Y
Shibata
Section of Preventive and Public Health Dentistry, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
Toru
T
Takeshita
Section of Preventive and Public Health Dentistry, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
Yoshihisa
Y
Yamashita
D024881:Drug Resistance, Bacterial / Q000235:genetics; D005459:Fluorides / Q000494:pharmacology*; D005798:Genes, Bacterial / Q000235:genetics; D006801:Humans; D007473:Ion Channels / Q000235:genetics / Q000502:physiology*; D009055:Mouth / Q000382:microbiology; D013291:Streptococcus / Q000187:drug effects* / Q000235:genetics; D034366:Streptococcus anginosus / Q000187:drug effects / Q000235:genetics; D054773:Streptococcus gordonii / Q000187:drug effects / Q000235:genetics; D034367:Streptococcus intermedius / Q000187:drug effects / Q000235:genetics; D013295:Streptococcus mutans / Q000187:drug effects / Q000235:genetics; D019533:Streptococcus oralis / Q000187:drug effects / Q000235:genetics; D000070001:Streptococcus salivarius / Q000187:drug effects / Q000235:genetics; D016986:Streptococcus sobrinus / Q000187:drug effects / Q000235:genetics
D007473:Ion Channels; D005459:Fluorides