The ylbH RNA motif is a putative regulatory element found upstream of the ylbH genes in spore-forming bacteria of the Bacillales order of Firmicutes [15096624]. The ylbH motif sequence overlaps with a small non-coding RNA gene (csfG) that is transcribed from the opposed strand and is expressed only during sporulation [21532344]. Since the csfG sRNA is preceded by a sigma-F controlled promoter, and is ended by a rho-independent transcription terminator [], it is most likely functions as a small regulatory RNA. The proposed RNA secondary structures of the ylbH motif [15096624], and of the complementary csfG RNAs [21532344] do not have the base stem RNA structure, that would allow the formation of compact aptamer domain, suggesting this conserved RNA is not a riboswitch but a small trans-acting RNA that controls expression of yet unknown genes involved in sporulation.