title: Role of sortase in Streptococcus mutans under the effect of nicotine.
abstract: Streptococcus mutans is a common Gram-positive bacterium and plays a significant role in dental caries. Tobacco and/or nicotine have documented effects on S. mutans growth and colonization. Sortase A is used by many Gram-positive bacteria, including S. mutans, to facilitate the insertion of certain cell surface proteins, containing an LPXTGX motif such as antigen I/II. This study examined the effect of nicotine on the function of sortase A to control the physiology and growth of S. mutans using wild-type S. mutans NG8, and its isogenic sortase-defective and -complemented strains. Briefly, the strains were treated with increasing amounts of nicotine in planktonic growth, biofilm metabolism, and sucrose-induced and saliva-induced antigen I/II-dependent biofilm formation assays. The strains exhibited no significant differences with different concentrations of nicotine in planktonic growth assays. However, they had significantly increased (P≤0.05) biofilm metabolic activity (2- to 3-fold increase) as the concentration of nicotine increased. Furthermore, the sortase-defective strain was more sensitive metabolically to nicotine than the wild-type or sortase-complemented strains. All strains had significantly increased sucrose-induced biofilm formation (2- to 3-fold increase) as a result of increasing concentrations of nicotine. However, the sortase-defective strain was not able to make as much sucrose- and saliva-induced biofilm as the wild-type NG8 did with increasing nicotine concentrations. These results indicated that nicotine increased metabolic activity and sucrose-induced biofilm formation. The saliva-induced biofilm formation assay and qPCR data suggested that antigen I/II was upregulated with nicotine but biofilm was not able to be formed as much as wild-type NG8 without functional sortase A.
authors.affiliation: 1] School of Dentistry, Indiana University, Indianapolis, USA [2] State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Ming-Yun
authors.initials: MY
authors.lastname: Li
authors.forename: Rui-Jie
authors.initials: RJ
authors.lastname: Huang
authors.forename: Xue-Dong
authors.initials: XD
authors.lastname: Zhou
authors.forename: Richard L
authors.initials: RL
authors.lastname: Gregory
mesh_terms: D020816:Amino Acid Motifs; D019881:Aminoacyltransferases / Q000187:drug effects* / Q000235:genetics; D000942:Antigens, Bacterial / Q000187:drug effects; D001422:Bacterial Adhesion / Q000187:drug effects; D001426:Bacterial Proteins / Q000187:drug effects* / Q000235:genetics; D018441:Biofilms / Q000187:drug effects; D003546:Cysteine Endopeptidases / Q000187:drug effects* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009154:Mutation / Q000235:genetics; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D010457:Peptidoglycan / Q000187:drug effects* / Q000235:genetics; D012463:Saliva / Q000502:physiology; D013295:Streptococcus mutans / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D013395:Sucrose / Q000494:pharmacology
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D010457:Peptidoglycan; D013395:Sucrose; D009538:Nicotine; D019881:Aminoacyltransferases; C120542:sortase A; D003546:Cysteine Endopeptidases