The Paralogous MarR/DUF24-Family Repressors YodB and CatR Control Expression of the Catechol Dioxygenase CatE inBacillus subtilis

Abstract

The redox-sensing MarR/DUF24-type repressor YodB controls expression of the azoreductase AzoR1 and the nitroreductase YodC that are involved in detoxification of quinones and diamide in Bacillus subtilis. In the present paper, we identified YodB and its paralog YvaP (CatR) as repressors of the yfiDE (catDE) operon encoding a catechol-2,3-dioxygenase that also contributes to quinone resistance. Inactivation of both CatR and YodB is required for full derepression of catDE transcription. DNA-binding assays and promoter mutagenesis studies showed that CatR protects two inverted repeats with the consensus sequence TTAC-N 5 -GTAA overlapping the ؊35 promoter region (BS1) and the transcriptional start site (TSS) (BS2). The BS1 operator was required for binding of YodB in vitro. CatR and YodB share the conserved N-terminal Cys residue, which is required for redox sensing of CatR in vivo as shown by Cys-to-Ser mutagenesis. Our data suggest that CatR is modified by intermolecular disulfide formation in response to diamide and quinones in vitro and in vivo. Redox regulation of CatR occurs independently of YodB, and no protein interaction was detected between CatR and YodB in vivo using protein cross-linking and mass spectrometry.Bacillus subtilis is exposed in the soil to a variety of antimicrobial agents that include phenolic and quinone-like compounds which are produced by other soil bacteria, plants, or fungi. In addition, quinone-like compounds are present in humic substances of the soil. Quinones are also biologically active compounds that function as lipid electron carriers in the electron transport chain (e.g., ubiquinone and menadione). Thus, quinones are naturally occurring electrophilic compounds that are ubiquitously distributed in bacterial systems.Proteomic and transcriptomic approaches revealed that catechol and methylhydroquinone (MHQ) act like diamide as thiol-reactive electrophiles in B. subtilis. Quinones and diamide deplete the cellular pool of low-molecular-weight (LMW) thiols via different mechanisms. Diamide leads to an increase in reversible thiol modifications, such as inter-and intramolecular disulfides and S thiolations (disulfides between proteins and LMW thiols) (9, 10, 27). Quinones can act as oxidants or electrophiles (13,20,25). As oxidants, quinones redox cycle with their semiquinones, producing reactive oxygen species (ROS), such as superoxide anion or hydrogen peroxide (18). The production of ROS could lead in turn to reversible thiol modifications. As electrophiles, quinones can form S adducts with cellular thiols via the thiol-(S)-alkylation chemistry. Recently, we showed that toxic quinones react mainly via S-alkylation with cellular thiol-containing proteins in vivo, which leads to aggregation and depletion of proteins in the proteome (18). However, we also found the glyceraldehyde-3-phosphate dehydrogenase GapA as a target for reversible thiol oxidation by quinones in vivo. Thus, quinones act via the oxidative and electrophilic mode in B. subtilis cells in vivo.The depletion of the th...

MarR-type Transcriptional Regulator ChlR Activates Expression of Tetrapyrrole Biosynthesis Genes in Response to Low-oxygen Conditions in Cyanobacteria

“…This motif would be a binding site for ChlR. This consensus sequence is very similar to that (TTAC-N 5 -GTAA) of CatR, which is a repressor of the catDE operon encoding catechol 2,3-dioxygenase for quinone resistance in B. subtilis (28).…”

Molecular mechanism of quinone signaling mediated through S-quinonization of a YodB family repressor QsrR

“…In Escherichia coli, the anoxic redox control ArcAB is considered a quinone-sensing two-component system (17,18). In Bacillus subtilis, the thiol-stress sensing regulator YodB is a prototypical transcriptional regulator responsible for quinone sensing and detoxification (19)(20)(21).…”

Structural insights into the redox-switch mechanism of the MarR/DUF24-type regulator HypR

“…Primer extension analysis was performed using the labelled primers as described previously (25). Sequencing of the corresponding promoter regions was performed using PCR products as templates containing the promoter region of the respective genes amplified with primer set yybR-C14S-for1 and yybR-Cys14S-rev1 and yfkO-FT-for2 and yfkO-FT-rev2 (Supplementary Table S2).…”