title: Association of CiaRH with resistance of Streptococcus mutans to antimicrobial peptides in biofilms.
abstract: Streptococcus mutans is a cariogenic pathogen in humans. To persist in the oral cavity, S. mutans is resistant against several antibacterial factors derived from the host. In this study, we investigated the mechanism of resistance to cationic antimicrobial peptides (AMPs), which are innate immune factors in humans. Because dltA-D (teichoic acid biosynthesis) was reported to affect the susceptibility to AMPs in other bacterial species, we evaluated the susceptibility of a dltC knockout mutant of S. mutans to the AMPs human beta-defensin-1 (hBD1), hBD2, hBD3 and LL37. The dltC mutant exhibited significantly increased susceptibility to AMPs. Regulation of dltC expression involved CiaRH, a two-component system. Expression of dltC in the wild-type strain was significantly increased in biofilm cells compared with that in planktonic cells, whereas expression was not increased in a ciaRH knockout mutant. In biofilm cells, we found that susceptibility to LL37 was increased in the ciaRH mutant compared with that in the wild type. From these results, it is concluded that Dlt is involved in the susceptibility of S. mutans to AMPs and is regulated by CiaRH in biofilm cells.
authors.affiliation: Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Mazda
authors.forename: M
authors.initials: M
authors.lastname: Kawada-Matsuo
authors.forename: K
authors.initials: K
authors.lastname: Kanbara
authors.forename: Y
authors.initials: Y
authors.lastname: Oogai
authors.forename: Y
authors.initials: Y
authors.lastname: Shibata
authors.forename: Y
authors.initials: Y
authors.lastname: Yamashita
authors.forename: S
authors.initials: S
authors.lastname: Miyawaki
authors.forename: H
authors.initials: H
authors.lastname: Komatsuzawa
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000502:physiology*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D018441:Biofilms; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D018085:Regulon / Q000502:physiology*; D013295:Streptococcus mutans / Q000502:physiology*; D014774:Virulence / Q000235:genetics
chemical_list: D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D002352:Carrier Proteins; C085651:D-alanyl carrier protein, bacteria