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

Autor(es)

Alves, Julia A. ^[1] ; Previato-Mello, Maristela ^[1] ; Barroso, Kelly C. M. ^[1] ; Koide, Tie ^[2] ; da Silva Neto, Jose F. ^[1]

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: BMC Microbiology; v. 21, n. 1 NOV 4 2021.
• Citações Web of Science: 0

Resumo

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)

• Processo FAPESP: 20/00259-8 - Papel de sistemas de secreção de Chromobacterium violaceum na interação com o hospedeiro e com outras bactérias
• Beneficiário: José Freire da Silva Neto
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 12/20435-9 - Fatores de transcrição de Chromobacterium violaceum: integrando vias de sinalização, regulons e patogenicidade
• Beneficiário: José Freire da Silva Neto
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 16/08728-1 - Estudo da função do fator de transcrição da família MarR CV3905 de Chromobacterium violaceum
• Beneficiário: Júlia Aparecida Alves
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 13/18797-2 - Expressão e purificação de fatores de transcrição de Chromobacterium violaceum
• Beneficiário: Kelly Cristina Martins Barroso
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 13/25745-9 - Caracterização funcional de fatores de transcrição da família MarR de Chromobacterium violaceum
• Beneficiário: Maristela Previato Mello
• Modalidade de apoio: Bolsas no Brasil - Doutorado