A novel TetR-like transcriptional regulator in Stenotrophomonas maltophilia is involved in fatty acid metabolism, including quorum sensing signal turnover

Stenotrophomonas maltophilia is an emerging opportunistic multidrug-resistant pathogen frequently co-isolated with other relevant nosocomial pathogens in respiratory tract infections. S. maltophilia uses the endogenous DSF quorum sensing (QS) system to regulate virulence processes but can also respond to exogenous AHL signals produced by neighboring bacteria. A whole-transcriptome sequencing analysis was performed for S. maltophilia strain K279a in the exponential and stationary phases and in exponential cultures after a treatment with exogenous DSF or AHLs. Among the common top upregulated genes, the putative TetR-like regulator Smlt2053 was selected for functional characterization. This regulator was found to sense long-chain fatty acids, including the QS signal DSF, and activate a β-oxidation catabolic pathway. In total six samples were analyzed (2 different conditions with three independent samples), and all cultures were done in LB at 37C and samples collected at an OD550 of 1.5. S. maltophilia K279aΔsmlt2053 mutant was compared to its wild type variant.