Uncovering the regulatory network of the small RNA SuhB and its contribution to stress resistance in Sphingopyxis granuli TFA

Abstract

Post-transcriptional regulation by small RNAs (sRNAs) enables bacteria to fine-tune gene expression and rapidly adapt to fluctuating environmental conditions. In Sphingopyxis granuli TFA, SuhB, the only sRNA characterized to date in this strain, was previously shown to repress thnR translation to control tetralin degradation under carbon catabolite repression conditions. Here, we reveal additional regulatory roles of SuhB beyond carbon metabolism. Deletion of suhB increases sensitivity to diverse abiotic stresses, including osmotic, oxidative, desiccation, and copper stress. Label-free quantitative proteomic analysis indicates widespread alterations in the proteome in the absence of SuhB, affecting metabolic pathways and membrane-associated processes. Moreover, a LysR-type transcription factor mutant, identified as a direct activator of suhB, shows similar phenotypes. Together, these findings demonstrate that SuhB functions as a global post-transcriptional regulator, coordinating metabolic balance, membrane composition, and stress resistance in S. granuli TFA, highlighting the critical role of sRNA-mediated regulation in environmental bacteria.