A cis-encoded RNA interaction controls sub-operonic spoVG expression in Staphylococcus aureus

Bacterial operons enable co-transcription of multiple genes, yet post-transcriptional mechanisms permitting differential regulation of individual genes within a polycistronic transcript remains incompletely understood. We demonstrate that a cis-encoded RNA-RNA interaction within the bicistronic yabJ-spoVG transcript forms an RNase III substrate that represses the transcription factor SpoVG in Staphylococcus aureus. Disruption of the cis-encoded regulation elevated monocistronic spoVG expression, reduced biofilm formation and cell wall peptidoglycan thickness, and increased sensitivity to cell wall-targeting antimicrobials in clinical vancomycin-intermediate S. aureus, consistent with phenotypes observed in an independent SpoVG overexpression strain. These findings uncover a previously undescribed mode of cis-regulatory control within a polycistronic operon and establish regulatory mRNA-mRNA interactions as a mechanism for sub-operonic gene regulation.