Browse
Submit Data
Databases
API
Help

Dataset Information

16 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Structural insight into the oxidation-sensing mechanism of the antibiotic resistance of regulator MexR.

ABSTRACT: MexR functions as the primary regulator of the mexAB-oprM multidrug efflux expression in Pseudomonas aeruginosa. It has been shown that MexR senses oxidative stress by interprotomer disulphide bond formation between redox-active cysteines. This oxidation induces MexR to dissociate from the promoter DNA, thus activating the transcriptional expression of efflux pump genes. In this study, we present the crystal structure of MexR in its oxidized form at a resolution of 2.1 A. This crystal structure reveals the mechanism by which oxidative signal allosterically derepresses the MexR-controlled transcription activation.

SUBMITTER: Chen H

PROVIDER: S-EPMC2933878 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Structural insight into the oxidation-sensing mechanism of the antibiotic resistance of regulator MexR.

Chen Hao H Yi Chengqi C Zhang Jin J Zhang Wenru W Ge Zhiyun Z Yang Cai-Guang CG He Chuan C

EMBO reports 20100709 9

MexR functions as the primary regulator of the mexAB-oprM multidrug efflux expression in Pseudomonas aeruginosa. It has been shown that MexR senses oxidative stress by interprotomer disulphide bond formation between redox-active cysteines. This oxidation induces MexR to dissociate from the promoter DNA, thus activating the transcriptional expression of efflux pump genes. In this study, we present the crystal structure of MexR in its oxidized form at a resolution of 2.1 A. This crystal structure ...[more]

PMID: 20616806

Similar Datasets

The Pseudomonas aeruginosa multidrug efflux regulator MexR uses an oxidation-sensing mechanism.

Project description:MexR is a MarR family protein that negatively regulates multidrug efflux systems in the human pathogen Pseudomonas aeruginosa. The mechanism of MexR-regulated antibiotic resistance has never been elucidated in the past. We present here that two Cys residues in MexR are redox-active. They form intermonomer disulfide bonds in MexR dimer with a redox potential of -155 mV. This MexR oxidation leads to its dissociation from promoter DNA, derepression of the mexAB-oprM drug efflux operon, and increased antibiotic resistance of P. aeruginosa. We show computationally that the formation of disulfide bonds is consistent with a conformation change that prevents the oxidized MexR from binding to DNA. Collectively, the results reveal that MexR is a redox regulator that senses peroxide stress to mediate antibiotic resistance in P. aeruginosa.

| S-EPMC2533233 | biostudies-literature

The structure of the pleiotropic transcription regulator CodY provides insight into its GTP-sensing mechanism.

Project description:GTP and branched-chain amino acids (BCAAs) are metabolic sensors that are indispensable for the determination of the metabolic status of cells. However, their molecular sensing mechanism remains unclear. CodY is a unique global transcription regulator that recognizes GTP and BCAAs as specific signals and affects expression of more than 100 genes associated with metabolism. Herein, we report the first crystal structures of the full-length CodY complex with sensing molecules and describe their functional states. We observed two different oligomeric states of CodY: a dimeric complex of CodY from Staphylococcus aureus with the two metabolites GTP and isoleucine, and a tetrameric form (apo) of CodY from Bacillus cereus Notably, the tetrameric state shows in an auto-inhibitory manner by blocking the GTP-binding site, whereas the binding sites of GTP and isoleucine are clearly visible in the dimeric state. The GTP is located at a hinge site between the long helical region and the metabolite-binding site. Together, data from structural and electrophoretic mobility shift assay analyses improve understanding of how CodY senses GTP and operates as a DNA-binding protein and a pleiotropic transcription regulator.

| S-EPMC5100569 | biostudies-literature

A New Way of Sensing: Need-Based Activation of Antibiotic Resistance by a Flux-Sensing Mechanism.

Project description:UnlabelledSensing of and responding to environmental changes are of vital importance for microbial cells. Consequently, bacteria have evolved a plethora of signaling systems that usually sense biochemical cues either via direct ligand binding, thereby acting as "concentration sensors," or by responding to downstream effects on bacterial physiology, such as structural damage to the cell. Here, we describe a novel, alternative signaling mechanism that effectively implements a "flux sensor" to regulate antibiotic resistance. It relies on a sensory complex consisting of a histidine kinase and an ABC transporter, in which the transporter fulfills the dual role of both the sensor of the antibiotic and the mediator of resistance against it. Combining systems biological modeling with in vivo experimentation, we show that these systems in fact respond to changes in activity of individual resistance transporters rather than to changes in the antibiotic concentration. Our model shows that the cell thereby adjusts the rate of de novo transporter synthesis to precisely the level needed for protection. Such a flux-sensing mechanism may serve as a cost-efficient produce-to-demand strategy, controlling a widely conserved class of antibiotic resistance systems.ImportanceBacteria have to be able to accurately perceive their environment to allow adaptation to changing conditions. This is usually accomplished by sensing the concentrations of beneficial or harmful substances or by measuring the effect of the prevailing conditions on the cell. Here we show the existence of a new way of sensing the environment, where the bacteria monitor the activity of an antibiotic resistance transporter. Such a "flux-sensing" mechanism allows the cell to detect its current capacity to deal with the antibiotic challenge and thus precisely respond to the need for more transporters. We propose that this is a cost-efficient way of regulating antibiotic resistance on demand.

| S-EPMC4513084 | biostudies-literature

Molecular Mechanisms of Master Regulator VqsM mediating Quorum-sensing and Antibiotic Resistance in Pseudomonas aeruginosa

Project description:The Pseudomonas aeruginosa quorum-sensing (QS) systems contribute to bacterial homeostasis and pathogenicity. Although the AraC family transcription factor VqsM has been characterized to control the production of virulence factors and QS signaling molecules, its detailed regulatory mechanisms still remain elusive. Here, we report that VqsM directly binds to the lasI promoter region, and thus regulates its expression. To identify additional targets of VqsM in P. aeruginosa PAO1, we performed chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq) which detected 48 enriched loci harboring VqsM-binding peaks in P. aeruginosa genome. The direct regulation of these genes by VqsM has been confirmed by Electrophoretic mobility shift assays (EMSAs) and quantitative real-time polymerase chain reactions (qRT-PCR). A VqsM-binding motif is found by using MEME suite and verified by footprint assays in vitro. In addition, VqsM directly binds to the promoter regions of antibiotic resistance regulator NfxB and the master type III system regulator ExsA. Notably, the vqsM mutant displayed more resistance to two types of antibiotics and promoted bacterial survival in a mouse model, compared to the wild type PAO1 strain. Collectively, this work provides new cues to better understand the detailed regulatory networks of QS systems, T3SS, and antibiotic resistance. Pseudomonas aeruginosa MAPO1 containing empty pAK1900 or pAK1900-VqsM-VSV

2014-08-04 | E-GEOD-57284 | biostudies-arrayexpress

Insight into the Mechanism of CO Oxidation on WO₃(001) Surfaces for Gas Sensing: A DFT Study.

Project description:The mechanism of CO oxidation on the WO₃(001) surface for gas sensing performance has been systematically investigated by means of first principles density functional theory (DFT) calculations. Our results show that the oxidation of CO molecule on the perfect WO₃(001) surface induces the formation of surface oxygen vacancies, which results in an increase of the surface conductance. This defective WO₃(001) surface can be re-oxidized by the O₂ molecules in the atmosphere. During this step, the active O₂- species is generated, accompanied with the obvious charge transfer from the surface to O₂ molecule, and correspondingly, the surface conductivity is reduced. The O₂- species tends to take part in the subsequent reaction with the CO molecule, and after releasing CO₂ molecule, the perfect WO₃(001) surface is finally reproduced. The activation energy barriers and the reaction energies associated with above surface reactions are determined, and from the kinetics viewpoint, the oxidation of CO molecule on the perfect WO₃(001) surface is the rate-limiting step with an activation barrier of about 0.91 eV.

| S-EPMC5579943 | biostudies-literature

Molecular mechanisms of master regulator VqsM mediating quorum-sensing and antibiotic resistance in Pseudomonas aeruginosa.

Project description:The Pseudomonas aeruginosa quorum-sensing (QS) systems contribute to bacterial homeostasis and pathogenicity. Although the AraC-family transcription factor VqsM has been characterized to control the production of virulence factors and QS signaling molecules, its detailed regulatory mechanisms still remain elusive. Here, we report that VqsM directly binds to the lasI promoter region, and thus regulates its expression. To identify additional targets of VqsM in P. aeruginosa PAO1, we performed chromatin immunoprecipitation (ChIP) followed by high-throughput DNA sequencing (ChIP-seq) and detected 48 enriched loci harboring VqsM-binding peaks in the P. aeruginosa genome. The direct regulation of these genes by VqsM has been confirmed by electrophoretic mobility shift assays and quantitative real-time polymerase chain reactions. A VqsM-binding motif was identified by using the MEME suite and verified by footprint assays in vitro. In addition, VqsM directly bound to the promoter regions of the antibiotic resistance regulator NfxB and the master type III secretion system (T3SS) regulator ExsA. Notably, the vqsM mutant displayed more resistance to two types of antibiotics and promoted bacterial survival in a mouse model, compared to wild-type PAO1. Collectively, this work provides new cues to better understand the detailed regulatory networks of QS systems, T3SS, and antibiotic resistance.

| S-EPMC4176358 | biostudies-literature

Molecular Mechanisms of Master Regulator VqsM mediating Quorum-sensing and Antibiotic Resistance in Pseudomonas aeruginosa

2014-08-04 | GSE57284 | GEO

Staphylococcus aureus CymR is a new thiol-based oxidation-sensing regulator of stress resistance and oxidative response.

Project description:As a human pathogen, Staphylococcus aureus must cope with oxidative stress generated by the human immune system. Here, we report that CymR utilizes its sole Cys-25 to sense oxidative stress. Oxidation followed by thiolation of this cysteine residue leads to dissociation of CymR from its cognate promoter DNA. In contrast, the DNA binding of the CymRC25S mutant was insensitive to oxidation and thiolation, suggesting that CymR senses oxidative stress through oxidation of its sole cysteine to form a mixed disulfide with low molecular weight thiols. The determined crystal structures of the reduced and oxidized forms of CymR revealed that Cys-25 is oxidized to Cys-25-SOH in the presence of H(2)O(2). Deletion of cymR reduced the resistance of S. aureus to oxidative stresses, and the resistance was restored by expressing a C25S mutant copy of cymR. In a C25S substitution mutant, the expression of two genes, tcyP and mccB, was constitutively repressed and did not respond to hydrogen peroxide stress, whereas the expression of the genes were highly induced under oxidative stress in a wild-type strain, indicating the critical role of Cys-25 in redox signaling in vivo. Thus, CymR is another master regulator that senses oxidative stress and connects stress responses to virulence regulation in S. aureus.

| S-EPMC3375533 | biostudies-literature

Critical biophysical properties in the Pseudomonas aeruginosa efflux gene regulator MexR are targeted by mutations conferring multidrug resistance.

Project description:The self-assembling MexA-MexB-OprM efflux pump system, encoded by the mexO operon, contributes to facile resistance of Pseudomonas aeruginosa by actively extruding multiple antimicrobials. MexR negatively regulates the mexO operon, comprising two adjacent MexR binding sites, and is as such highly targeted by mutations that confer multidrug resistance (MDR). To understand how MDR mutations impair MexR function, we studied MexR-wt as well as a selected set of MDR single mutants distant from the proposed DNA-binding helix. Although DNA affinity and MexA-MexB-OprM repression were both drastically impaired in the selected MexR-MDR mutants, MexR-wt bound its two binding sites in the mexO with high affinity as a dimer. In the MexR-MDR mutants, secondary structure content and oligomerization properties were very similar to MexR-wt despite their lack of DNA binding. Despite this, the MexR-MDR mutants showed highly varying stabilities compared with MexR-wt, suggesting disturbed critical interdomain contacts, because mutations in the DNA-binding domains affected the stability of the dimer region and vice versa. Furthermore, significant ANS binding to MexR-wt in both free and DNA-bound states, together with increased ANS binding in all studied mutants, suggest that a hydrophobic cavity in the dimer region already shown to be involved in regulatory binding is enlarged by MDR mutations. Taken together, we propose that the biophysical MexR properties that are targeted by MDR mutations-stability, domain interactions, and internal hydrophobic surfaces-are also critical for the regulation of MexR DNA binding.

| S-EPMC2867009 | biostudies-literature

A novel antibiotic resistance mechanism

Project description:A novel antibiotic resistance mechanism

| PRJEB25942 | ENA