부산대학교 도서관

ABSTRACTSmall noncoding RNAs (sRNAs) have been identified as important regulators of gene expression in various cellular processes. cia-dependent small RNAs (csRNAs), a group of sRNAs that are controlled by the two-component regulatory system CiaRH, are widely conserved in streptococci, but their targets have been identified only in Streptococcus pneumoniae. Streptococcus sanguinis, a pioneer colonizer of teeth and one of the most predominant bacteria in the early oral biofilm, has been shown to have six csRNAs. Using computational target prediction and the luciferase reporter assay, we identified pilT, a constituent of the type IV pilus operon, as a negative regulatory target for one of the csRNAs, namely, csRNA1-1, in S. sanguinis. RNA-RNA electrophoretic mobility shift assay using a nucleotide exchange mutant of csRNA1-1 revealed that csRNA1-1 binds directly to pilTmRNA. In addition, csRNA1-1 and csRNA1-2, a putative gene duplication product of csRNA1-1 that is tandemly located in the S. sanguinisgenome, negatively regulated S. sanguinisbiofilm formation. These results suggest the involvement of csRNAs in the colonization step of S. sanguinis.