The MarR family regulator OsbR controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in Chromobacterium violaceum

Abstract Background Chromobacterium violaceum is an environmental opportunistic pathogen that causes rare but deadly infections in humans. The transcriptional regulators that C. violaceum uses to sense and respond to environmental cues remain largely unknown. Results Here, we described a novel trans...

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Autores principales:	Júlia A. Alves, Maristela Previato-Mello, Kelly C. M. Barroso, Tie Koide, José F. da Silva Neto
Formato:	article
Lenguaje:	EN
Publicado:	BMC 2021
Materias:	Chromobacterium violaceum MarR family regulator OsbR regulon Transcriptome analysis Oxidative stress Biofilm formation Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/8cf0c0561f9044f98ccc3c8c845e2820
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spelling	oai:doaj.org-article:8cf0c0561f9044f98ccc3c8c845e28202021-11-07T12:09:03ZThe MarR family regulator OsbR controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in Chromobacterium violaceum10.1186/s12866-021-02369-x1471-2180https://doaj.org/article/8cf0c0561f9044f98ccc3c8c845e28202021-11-01T00:00:00Zhttps://doi.org/10.1186/s12866-021-02369-xhttps://doaj.org/toc/1471-2180Abstract Background Chromobacterium violaceum is an environmental opportunistic pathogen that causes rare but deadly infections in humans. The transcriptional regulators that C. violaceum uses to sense and respond to environmental cues remain largely unknown. Results Here, we described a novel transcriptional regulator in C. violaceum belonging to the MarR family that we named OsbR (oxidative stress response and biofilm formation regulator). Transcriptome profiling by DNA microarray using strains with deletion or overexpression of osbR showed that OsbR exerts a global regulatory role in C. violaceum, regulating genes involved in oxidative stress response, nitrate reduction, biofilm formation, and several metabolic pathways. EMSA assays showed that OsbR binds to the promoter regions of several OsbR-regulated genes, and the in vitro DNA binding activity was inhibited by oxidants. We demonstrated that the overexpression of osbR caused activation of ohrA even in the presence of the repressor OhrR, which resulted in improved growth under organic hydroperoxide treatment, as seem by growth curve assays. We showed that the proper regulation of the nar genes by OsbR ensures optimal growth of C. violaceum under anaerobic conditions by tuning the reduction of nitrate to nitrite. Finally, the osbR overexpressing strain showed a reduction in biofilm formation, and this phenotype correlated with the OsbR-mediated repression of two gene clusters encoding putative adhesins. Conclusions Together, our data indicated that OsbR is a MarR-type regulator that controls the expression of a large number of genes in C. violaceum, thereby contributing to oxidative stress defense (ohrA/ohrR), anaerobic respiration (narK1K2 and narGHJI), and biofilm formation (putative RTX adhesins).Júlia A. AlvesMaristela Previato-MelloKelly C. M. BarrosoTie KoideJosé F. da Silva NetoBMCarticleChromobacterium violaceumMarR family regulatorOsbR regulonTranscriptome analysisOxidative stressBiofilm formationMicrobiologyQR1-502ENBMC Microbiology, Vol 21, Iss 1, Pp 1-14 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Chromobacterium violaceum MarR family regulator OsbR regulon Transcriptome analysis Oxidative stress Biofilm formation Microbiology QR1-502
spellingShingle	Chromobacterium violaceum MarR family regulator OsbR regulon Transcriptome analysis Oxidative stress Biofilm formation Microbiology QR1-502 Júlia A. Alves Maristela Previato-Mello Kelly C. M. Barroso Tie Koide José F. da Silva Neto The MarR family regulator OsbR controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in Chromobacterium violaceum
description	Abstract Background Chromobacterium violaceum is an environmental opportunistic pathogen that causes rare but deadly infections in humans. The transcriptional regulators that C. violaceum uses to sense and respond to environmental cues remain largely unknown. Results Here, we described a novel transcriptional regulator in C. violaceum belonging to the MarR family that we named OsbR (oxidative stress response and biofilm formation regulator). Transcriptome profiling by DNA microarray using strains with deletion or overexpression of osbR showed that OsbR exerts a global regulatory role in C. violaceum, regulating genes involved in oxidative stress response, nitrate reduction, biofilm formation, and several metabolic pathways. EMSA assays showed that OsbR binds to the promoter regions of several OsbR-regulated genes, and the in vitro DNA binding activity was inhibited by oxidants. We demonstrated that the overexpression of osbR caused activation of ohrA even in the presence of the repressor OhrR, which resulted in improved growth under organic hydroperoxide treatment, as seem by growth curve assays. We showed that the proper regulation of the nar genes by OsbR ensures optimal growth of C. violaceum under anaerobic conditions by tuning the reduction of nitrate to nitrite. Finally, the osbR overexpressing strain showed a reduction in biofilm formation, and this phenotype correlated with the OsbR-mediated repression of two gene clusters encoding putative adhesins. Conclusions Together, our data indicated that OsbR is a MarR-type regulator that controls the expression of a large number of genes in C. violaceum, thereby contributing to oxidative stress defense (ohrA/ohrR), anaerobic respiration (narK1K2 and narGHJI), and biofilm formation (putative RTX adhesins).
format	article
author	Júlia A. Alves Maristela Previato-Mello Kelly C. M. Barroso Tie Koide José F. da Silva Neto
author_facet	Júlia A. Alves Maristela Previato-Mello Kelly C. M. Barroso Tie Koide José F. da Silva Neto
author_sort	Júlia A. Alves
title	The MarR family regulator OsbR controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in Chromobacterium violaceum
title_short	The MarR family regulator OsbR controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in Chromobacterium violaceum
title_full	The MarR family regulator OsbR controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in Chromobacterium violaceum
title_fullStr	The MarR family regulator OsbR controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in Chromobacterium violaceum
title_full_unstemmed	The MarR family regulator OsbR controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in Chromobacterium violaceum
title_sort	marr family regulator osbr controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in chromobacterium violaceum
publisher	BMC
publishDate	2021
url	https://doaj.org/article/8cf0c0561f9044f98ccc3c8c845e2820
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The MarR family regulator OsbR controls oxidative stress response, anaerobic nitrate respiration, and biofilm formation in Chromobacterium violaceum

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