RESUMO
Quinone molecules are intracellular electron-transport carriers, as well as critical intra- and extracellular signals. However, transcriptional regulation of quinone signaling and its molecular basis are poorly understood. Here, we identify a thiol-stress-sensing regulator YodB family transcriptional regulator as a central component of quinone stress response of Staphylococcus aureus, which we have termed the quinone-sensing and response repressor (QsrR). We also identify and confirm an unprecedented quinone-sensing mechanism based on the S-quinonization of the essential residue Cys-5. Structural characterizations of the QsrR-DNA and QsrR-menadione complexes further reveal that the covalent association of menadione directly leads to the release of QsrR from operator DNA following a 10° rigid-body rotation as well as a 9-Å elongation between the dimeric subunits. The molecular level characterization of this quinone-sensing transcriptional regulator provides critical insights into quinone-mediated gene regulation in human pathogens.
Assuntos
Proteínas de Bactérias , Benzoquinonas , Processamento de Proteína Pós-Traducional/fisiologia , Proteínas Repressoras , Transdução de Sinais/fisiologia , Staphylococcus aureus , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Benzoquinonas/química , Benzoquinonas/metabolismo , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Humanos , Estrutura Quaternária de Proteína , Estrutura Terciária de Proteína , Proteínas Repressoras/química , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Staphylococcus aureus/química , Staphylococcus aureus/genética , Staphylococcus aureus/metabolismoRESUMO
Mycobacterium tuberculosis thrives in oxidative environments such as the macrophage. To survive, the bacterium must sense and adapt to the oxidative conditions. Several antioxidant defenses including a thick cell wall, millimolar concentrations of small molecule thiols, and protective enzymes are known to help the bacterium withstand the oxidative stress. However, oxidation-sensing regulators that control these defenses have remained elusive. In this study, we report a new oxidation-sensing regulator, Rv1049 or MosR (M. tuberculosis oxidation-sensing regulator). MosR is a transcriptional repressor of the MarR family, which, similarly to Bacillus subtilis OhrR and Staphylococcus aureus MgrA, dissociates from DNA in the presence of oxidants, enabling transcription. MosR senses oxidation through a pair of cysteines near the N terminus (Cys-10 and Cys-12) that upon oxidation forms a disulfide bond. Disulfide formation rearranges a network of hydrogen bonds, which leads to a large conformational change of the protein and dissociation from DNA. MosR has been shown previously to play an important role in survival of the bacterium in the macrophage. In this study, we show that the main role of MosR is to up-regulate expression of rv1050 (a putative exported oxidoreductase that has not yet been characterized) in response to oxidants and propose that it is through this role that MosR contributes to the bacterium survival in the macrophage.
Assuntos
Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Mycobacterium tuberculosis/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Sequência de Bases , Cristalografia por Raios X , Cisteína/química , Cisteína/genética , Cisteína/metabolismo , DNA/química , DNA/genética , DNA/metabolismo , Dissulfetos/química , Dissulfetos/metabolismo , Eletroforese em Gel de Poliacrilamida , Perfilação da Expressão Gênica , Peróxido de Hidrogênio/farmacologia , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Mycobacterium tuberculosis/metabolismo , Conformação de Ácido Nucleico , Motivos de Nucleotídeos/genética , Oxidantes/farmacologia , Oxirredução , Regiões Promotoras Genéticas/genética , Ligação Proteica/efeitos dos fármacos , Estrutura Terciária de Proteína , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de Aminoácidos , Fatores de Transcrição/química , Fatores de Transcrição/metabolismoRESUMO
OBJECTIVE: To identify patient and neighborhood factors associated with health center (HC) use. METHODS: A cross-sectional study of Medicaid fee-for-service claims in 2009 comparing HC users and nonusers. RESULTS: Dually eligible patients (odds ratio [OR] 95% CI = [0.60, 0.61]) and those with high chronic disease burden (OR 95% CI = [0.73, 0.74]) had lower odds of HC use. Temporary Assistance for Needy Families participants (OR 95% CI = [1.20, 1.24]), black (OR 95% CI = [1.33, 1.36]) and Hispanic (OR 95% CI = [1.22, 1.25]) beneficiaries had higher odds. Local HC presence predicted higher HC use (OR 95% CI = [2.63, 2.70]). CONCLUSION: Findings may be useful in steering HC policies affecting critical access for Medicaid beneficiaries.