The two‐component system TarR–TarS is regulated by c‐di‐GMP / FleQ and FliA and modulates antibiotic susceptibility in Pseudomonas putida

Summary Two‐component systems (TCSs) are predominant means by which bacteria sense and respond to environment signals. Genome of Pseudomonas putida contains dozens of putative TCS‐encoding genes, but phenotypical–genotypical correlation and transcriptional regulation of these genes are largely unknown. Herein, we characterized function and transcriptional regulation of a conserved P. putida TCS, named TarR–TarS. TarS ( PP_0769 ) encodes a potential histidine kinase, and tarR ( PP_0768 ) encodes a potential response regulator. Protein–protein interaction assay and phosphorylation assay confirmed that TarR–TarS was a functional TCS. Growth assay under antibiotics revealed that TarR–TarS positively regulated bacterial resistance to multiple antibiotics. Pull‐down assay revealed that TarR directly interacted with PP_0800 (a hypothetical protein) and GroEL (the chaperonin). GroEL played a positive role in antibiotic resistance, while PP_0800 seemed to have no effect on antibiotic resistance. The regulator FleQ indirectly activated tarR–tarS transcription. However, the second messenger c‐di‐GMP antagonized FleQ activation to inhibit tarR–tarS transcription. The sigma factor FliA directly activated tarR–tarS transcription via a consensus motif. These findings reveal function and transcriptional regulation of TarR – TarS, and enrich knowledge regarding the relationship between c‐di‐GMP and antibiotic susceptibility in P. putida .