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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

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Alves, Julia A. [1] ; Previato-Mello, Maristela [1] ; Barroso, Kelly C. M. [1] ; Koide, Tie [2] ; da Silva Neto, Jose F. [1]
Total Authors: 5
[1] Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Biol Celular & Mol & Bioagentes Patogen, Ribeirao Preto, SP - Brazil
[2] Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Bioquim & Imunol, Ribeirao Preto, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: BMC Microbiology; v. 21, n. 1 NOV 4 2021.
Web of Science Citations: 0

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). (AU)

FAPESP's process: 20/00259-8 - Role of secretion systems of Chromobacterium violaceum in the interaction with the host and other bacteria
Grantee:José Freire da Silva Neto
Support type: Regular Research Grants
FAPESP's process: 12/20435-9 - Transcription factors of Chromobacterium violaceum: integrating signaling pathways, regulons and pathogenicity
Grantee:José Freire da Silva Neto
Support type: Research Grants - Young Investigators Grants
FAPESP's process: 16/08728-1 - Study of the MarR family transcription factor CV3905 of Chromobacterium violaceum
Grantee:Júlia Aparecida Alves
Support type: Scholarships in Brazil - Scientific Initiation
FAPESP's process: 13/25745-9 - Functional characterization of MarR family transcription factors in Chromobacterium violaceum
Grantee:Maristela Previato Mello
Support type: Scholarships in Brazil - Doctorate