Insight into the Effect of Small RNA on Mutacin IV in .

() is a serious microbe causing dental caries. Mutacin IV is an effective bacteriocin produced by to antagonize numerous non-mutans streptococcal species. However, the posttranscriptional regulation of mutacin IV remains unclear. This study aimed to analyze the effect of small RNA on mutacin IV. The functional prediction suggested that is involved in the production of mutacin IV, an important secondary metabolite. According to RNAhybrid and RNAPredator prediction, the mutacin IV formation-associated gene is a target of . We further analyzed the roles of and in 20 clinical strains with high production of mutacin IV (High-IV group) and lacking mutacin IV (None-IV group). Levels of expression were significantly higher in the High-IV group, whereas the Non-IV group showed relatively higher expression of , with a negative correlation observed between and . Moreover, compared to the mimic negative control (NC) group, expression was decreased at 400-fold overexpression but increased at approximately 1400-fold overexpression. Although the production of mutacin IV in the 1400-fold change mimic group was larger than that in the 400-fold change mimic group, there was no significant difference in the production of mutacin IV between the mimic group and mimic NC group. These results indicate that has a two-way regulation effect on the expression of but that its regulation in the production of mutacin IV is weak.