The small RNA Teg16 represses rsbV and modulates SigB-dependent gene expression in Staphylococcus aureus

Abstract

Staphylococcus aureus relies on coordinated regulatory networks to adapt to environmental stress and host-associated conditions. The alternative sigma factor SigB plays a central role in this process and is controlled by the anti-anti-sigma factor RsbV, which functions as a key regulatory node in the pathway. While numerous small regulatory RNAs (sRNAs) have been identified in S. aureus, relatively few have been directly linked to the SigB stress response network. Here, we investigated the role of the small RNA Teg16 in post-transcriptional regulation of the SigB stress response pathway. Computational prediction identified a region of complementarity between Teg16 and the translational initiation region of rsbV. To test a potential regulatory effect based on this prediction, teg16 was overexpressed, and rsbV transcript levels were measured by quantitative RT-PCR. Teg16 overexpression resulted in reduced rsbV transcript levels and decreased expression of SigB-dependent genes, including asp23 and the carotenoid (crt) biosynthesis operon responsible for staphyloxanthin pigment production. In addition, strains carrying the teg16 expression construct exhibited altered hemolytic activity under the conditions tested, suggesting effects on virulence-associated phenotypes. We further examined whether Teg16 influences the global regulator CodY and observed reduced codY transcript levels at early time points following teg16 overexpression. Together, these results extend a previously identified regulatory relationship between Teg16 and CodY and raise the possibility of a feedback relationship linking post-transcriptional regulation to metabolic control. These findings identify Teg16 as a previously uncharacterized regulator that connects small RNA-mediated control to the SigB stress response network in S. aureus. ImportanceThe alternative sigma factor SigB is a central regulator of stress adaptation in Staphylococcus aureus and influences both metabolism and virulence-associated phenotypes. While numerous small regulatory RNAs (sRNAs) have been identified in this organism, few have been functionally linked to control of the SigB pathway. Here, we identify the small RNA Teg16 as a regulator of rsbV, a key modulator of SigB activity. Teg16-dependent repression of rsbV is associated with reduced expression of SigB-dependent genes and measurable changes in phenotype, including decreased pigment production and altered hemolytic activity. In addition, our findings extend a previously identified relationship between Teg16 and the global regulator CodY, suggesting integration of post-transcriptional regulation with metabolic control. These results establish Teg16 as a previously uncharacterized component of the SigB regulatory network and provide new insight into how small RNAs contribute to stress adaptation in S. aureus.