Characterization of a small non-coding RNA S612 in Bacillus subtilis

Small regulatory RNAs (sRNAs) are non-coding RNA molecules that fine-tune various cellular processes and respond to various environmental stimuli. In Bacillus subtilis, the regulatory mechanisms and specific targets of several sRNAs remain largely unknown. In this study, we identified and characterized S612 as a self-terminating sRNA in B. subtilis. The expression of S612 is regulated by external signals, including nutrient availability and salt concentration. Overexpression of S612 induced filamentous cells with extensive cellular elongation and complete inhibition of sporulation, indicating its potential to control cell morphology and spore formation. S612 directly targets and downregulates genes through post-transcriptional base pairing with mRNAs, including ylmD, trpE, ycxC, yycS, rapH, and amyE, some of which are involved in cell membrane integrity, cell wall synthesis, and sporulation initiation. Therefore, we propose that S612 is an important post-transcriptional regulator of cell morphology and sporulation.