Biologically functional and regulatory analysis of a two-component signal transduction system CgtSR1 in Corynebacterium glutamicum

The two-component systems (TCSs) are crucial for bacterial adaptation to environmental stresses and growth conditions. In Corynebacterium glutamicum, a model organism of Corynebacteriales, 13 TCSs have been identified, but only five of them have been characterized previously. The ncgl0269-ncgl0268 gene cluster, annotated as a putative TCS (designated as CgtSR1), remains unexplored in terms of its regulatory role and mechanism. In this study, we revealed that CgtSR1 might regulate the expression of antimicrobial efflux transporters (including secondary transporters and primary transporters-ATP-binding cassette (ABC)) by transcriptomic analysis. EMSA experiments confirmed that CgtR1 directly binds to the promoter regions of three secondary transporter genes (ncgl0887, ncgl1020, and ncgl1445). Phenotypic assays demonstrated that the deletion of cgtSR1 increased susceptibility to gentamicin and spectinomycin, whereas its overexpression conferred resistance. Additionally, overexpression of cgtSR1 enhanced tolerance of cells to resorcinol and 2,4-dihydroxybenzoate. This study elucidates the regulatory network of CgtSR1 and deepens the understanding of TCS-mediated stress adaptation in C. glutamicum, providing a basis for further mechanistic investigations.