1. The role of MfsR, a TetR-type transcriptional regulator, in adaptive protection of Stenotrophomonas maltophilia against benzalkonium chloride via the regulation of mfsQ.
- Author
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Chittrakanwong J, Charoenlap N, Vanitshavit V, Sowatad A, Mongkolsuk S, and Vattanaviboon P
- Subjects
- Gene Expression Regulation, Bacterial, Membrane Transport Proteins genetics, Operon, Phylogeny, Quaternary Ammonium Compounds pharmacology, Bacterial Proteins genetics, Bacterial Proteins metabolism, Benzalkonium Compounds pharmacology, Stenotrophomonas maltophilia classification, Stenotrophomonas maltophilia drug effects, Stenotrophomonas maltophilia genetics, Stenotrophomonas maltophilia metabolism
- Abstract
A gene encoding the TetR-type transcriptional regulator mfsR is located immediately downstream of mfsQ and is transcribed in the same transcriptional unit. mfsQ encodes a major facilitator superfamily (MFS) efflux transporter contributing to the resistance of Stenotrophomonas maltophilia towards disinfectants belonging to quaternary ammonium compounds (QACs), which include benzalkonium chloride (BAC). Phylogenetic analysis revealed that MfsR is closely related to CgmR, a QAC-responsive transcriptional regulator belonging to the TetR family. MfsR regulated the expression of the mfsQR operon in a QAC-inducible manner. The constitutively high transcript level of mfsQ in an mfsR mutant indicated that MfsR functions as a transcriptional repressor of the mfsQR operon. Electrophoretic mobility shift assays showed that purified MfsR specifically bound to the putative promoter region of mfsQR, and in vitro treatments with QACs led to the release of MfsR from binding complexes. DNase I protection assays revealed that the MfsR binding box comprises inverted palindromic sequences located between motifs -35 and -10 of the putative mfsQR promoter. BAC-induced adaptive protection was abolished in the mfsR mutant and was restored in the complemented mutant. Overall, MfsR is a QACs-sensing regulator that controls the expression of mfsQ. In the absence of QACs, MfsR binds to the box located in the mfsQR promoter and represses its transcription. The presence of QACs derepresses MfsR activity, allowing RNA polymerase binding and transcription of mfsQR. This MfsR-MsfQ system enables S. maltophilia to withstand high levels of QACs., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2021
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