The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
MarR Family: A large family of bacterial transcriptional regulators, originally named for the "Multiple antibiotic resistance Regulator" in Escherichia coli. MarR proteins commonly serve as repressors or dual-function transcription factors, modulating gene expression in response to environmental cues, toxins, metabolites, and oxidative stress. They are crucial for pathogen adaptation, stress resistance, and metabolic regulation (nazaret2023marrfamilytranscriptional pages 1-2, beggs2020marrfamilyproteins pages 1-2, beggs2020marrfamilyproteins pages 2-4).
Structural Features: MarR proteins are typically homodimeric, with a conserved winged helix-turn-helix (wHTH) DNA-binding domain. They recognize palindromic DNA sequences (~16–20 bp), often with additional specificity via the wing contacting the minor groove. Ligand binding (small molecule effectors or oxidative modification of cysteines) induces conformational changes that reduce DNA binding, derepressing target genes (nazaret2023marrfamilytranscriptional pages 1-2, beggs2020marrfamilyproteins pages 1-2, beggs2020marrfamilyproteins pages 2-4, nazaret2023marrfamilytranscriptional pages 2-4).
Stress Response and Virulence Regulation: Current studies on MarR family regulators in C. violaceum and other proteobacteria emphasize their roles in managing oxidative stress (e.g., peroxides/organic hydroperoxides), responding to environmental signals (phenolics, metals), and regulating key adaptations like virulence, exopolysaccharide synthesis, and aromatic compound degradation (nazaret2023marrfamilytranscriptional pages 4-6, previatomello2017globaltranscriptionalresponse pages 1-3).
Experimental Characterization: While direct experimental studies of Q7NUH2/CV_2726 are lacking, the MarR family member OhrR has been rigorously analyzed in C. violaceum. OhrR represses genes related to peroxide defense (notably ohrA) and c-di-GMP signaling; OhrR loss impairs virulence in animal models. These studies further support the family-level inference for Q7NUH2/CV_2726 regulatory roles (previatomello2017globaltranscriptionalresponse pages 1-3).
Primary Function: DNA-binding transcriptional regulator, most likely acting mainly as a repressor. The protein likely responds to small molecule ligands, oxidants, or metal ions, as is characteristic of MarR family members. Upon ligand binding or oxidative modification (e.g., cysteine oxidation), DNA affinity is lost, allowing expression of adjoining or regulon genes (nazaret2023marrfamilytranscriptional pages 1-2, nazaret2023marrfamilytranscriptional pages 2-4, nazaret2023marrfamilytranscriptional pages 4-6).
Regulated Pathways and Processes: By analogy to characterized MarR family proteins (including OhrR in C. violaceum), CV_2726 may be involved in:
Environmental adaptation in response to metals or organic contaminants
These roles are well-supported for MarR/OhrR regulators in bacteria and align with the domain structure of Q7NUH2 (nazaret2023marrfamilytranscriptional pages 4-6, previatomello2017globaltranscriptionalresponse pages 1-3).
Direct Evidence: No direct functional or mutational data exist for Q7NUH2/CV_2726. Thus, these functional annotations are based on high-confidence inference from conserved structure and regulatory logic within the MarR family (nazaret2023marrfamilytranscriptional pages 1-2, nazaret2023marrfamilytranscriptional pages 4-6).
A summary table is included below to consolidate available information, supporting evidence, and the degree of experimental or inferred status for Q7NUH2 in C. violaceum.
| Characteristic | Summary for Q7NUH2 / CV_2726 | Evidence |
|---|---|---|
| Protein Name/ID | UniProt Q7NUH2; ordered locus name CV_2726; annotated as a probable transcriptional regulator, MarR family | UniProt-derived target description; genome-scale annotation of C. violaceum ATCC 12472 supports the presence of this locus in the sequenced strain (vasconcelos2003thecompletegenome pages 1-2, vasconcelos2003thecompletegenome pages 3-4) |
| Organism | Chromobacterium violaceum strain ATCC 12472 / DSM 30191 / JCM 1249 / CCUG 213 / NBRC 12614 / NCIMB 9131 / NCTC 9757 / MK | The complete genome sequence analyzed was from C. violaceum type strain ATCC 12472 (vasconcelos2003thecompletegenome pages 1-2) |
| Protein Family | MarR-family transcriptional regulator | MarR proteins are widespread bacterial transcription factors that generally act as repressors and often regulate stress-adaptive responses (nazaret2023marrfamilytranscriptional pages 1-2, beggs2020marrfamilyproteins pages 1-2) |
| Key Domains | HTH_MarR-typ; MarR/SlyA-like; winged helix-turn-helix DNA-binding fold; MarR_2/PF12802 | MarR proteins characteristically contain a winged helix-turn-helix DNA-binding domain plus helices involved in dimerization (nazaret2023marrfamilytranscriptional pages 1-2, beggs2020marrfamilyproteins pages 1-2, beggs2020marrfamilyproteins pages 2-4) |
| Predicted Molecular Function | Sequence-specific DNA-binding transcriptional regulator, most likely functioning primarily as a repressor that modulates transcription of neighboring or regulon genes in response to chemical/redox signals | MarR-family proteins commonly repress transcription until ligand binding or oxidation lowers DNA affinity and derepresses target genes (nazaret2023marrfamilytranscriptional pages 1-2, beggs2020marrfamilyproteins pages 2-4, nazaret2023marrfamilytranscriptional pages 2-4) |
| DNA Binding Characteristics | Likely homodimeric DNA-binding protein recognizing palindromic operator DNA, typically ~16–20 bp; recognition helices contact adjacent major grooves and the wing can contact the minor groove | General MarR-family DNA-binding mode and operator architecture are well established from structural and biochemical studies (nazaret2023marrfamilytranscriptional pages 1-2, beggs2020marrfamilyproteins pages 1-2, beggs2020marrfamilyproteins pages 2-4) |
| Signal/Ligand Sensing | Exact ligand for CV_2726 is unknown; by family analogy it may respond to small molecules such as phenolics, antibiotics, metals, or redox-active/oxidative signals that alter DNA-binding affinity | MarR-family regulators sense phenolic compounds, antibiotics, urate, metals, and oxidants; signaling commonly occurs through allosteric ligand binding or cysteine oxidation (nazaret2023marrfamilytranscriptional pages 4-6, nazaret2023marrfamilytranscriptional pages 2-4) |
| Biological Processes Regulated | Specific regulon for CV_2726 has not been experimentally defined; by family inference likely involved in environmental stress adaptation, potentially including oxidative stress responses, aromatic/xenobiotic metabolism, metal response, or virulence-associated regulation | In C. violaceum, the MarR-family regulator OhrR controls peroxide defense genes and virulence-related traits, while broader MarR-family literature links these regulators to oxidative stress resistance, aromatic compound degradation, exopolysaccharide/virulence control, and adaptive signaling pathways (nazaret2023marrfamilytranscriptional pages 4-6, previatomello2017globaltranscriptionalresponse pages 1-3) |
| Subcellular Localization | Cytoplasmic DNA-binding regulator acting on chromosomal promoter/operator regions | MarR proteins act as intracellular transcription factors that bind target DNA in the bacterial cytoplasm/nucleoid compartment (nazaret2023marrfamilytranscriptional pages 1-2, beggs2020marrfamilyproteins pages 1-2) |
| Evidence Type (experimental vs inferred) | Direct evidence for Q7NUH2/CV_2726: genome annotation/domain-based assignment; no direct functional study identified for this specific protein. Strong inferred evidence from conserved MarR-family structure-function relationships and from experimentally characterized MarR regulators in C. violaceum such as OhrR | Annotation and genome evidence are direct for locus existence; function, ligand sensing, and pathway roles are inferred from family/domain conservation and organism-level MarR studies (vasconcelos2003thecompletegenome pages 1-2, nazaret2023marrfamilytranscriptional pages 1-2, previatomello2017globaltranscriptionalresponse pages 1-3) |
Table: This table summarizes what is known directly and what can be inferred for Q7NUH2/CV_2726 in Chromobacterium violaceum. It is useful because direct literature on this exact protein is limited, so the table distinguishes annotation-supported facts from family-based functional inference.
This report integrates current knowledge, recent literature, and direct experimental findings for MarR-family regulators in C. violaceum, supplemented by high-confidence family-wide inferences. For precise assignments regarding CV_2726 function, future dedicated mutational and biochemical studies are recommended.
References
(vasconcelos2003thecompletegenome pages 1-2): A. Vasconcelos, D. F. Almeida, M. Hungria, C. T. Guimarães, R. Antônio, F. Almeida, L. G. Almeida, R. Almeida, J. Alves-Gomes, Elizabeth M. Mazoni Andrade, J. Araripe, Magnólia Araújo, S. Astolfi-Filho, V. Azevedo, A. J. Baptista, L. A. Bataus, J. Batista, A. Beló, C. Berg, M. Bogo, S. Bonatto, J. Bordignon, Marcelo M. Macedo Brigidom, C. Brito, M. Brocchi, H. A. Burity, A. Camargo, D. D. Cardoso, N. Carneiro, D. Carraro, C. Carvalho, J. Cascardo, B. Cavada, L. M. O. Chueire, T. Creczynski-Pasa, Nivaldo C. Costa Da Cunha-Junior, N. J. Fagundes, Clarissa Lima Falão, F. Fantinatti, I. Farias, M. Felipe, Lilian Pereira Ferrari, J. Ferro, M. Ferro, G. Franco, N. S. A. Freitas, L. R. Furlan, R. Gazzinelli, E. Gomes, P. Gonçalves, T. B. Grangeiro, D. Grattapaglia, E. Grisard, E. S. Hanna, S. N. Jardim, J. Laurino, Lélia Cristina Tenório Leoi, L. F. A. Lima, M. F. Loureiro, M. D. C. C. P. Lyra, H. Madeira, G. Manfio, A. Maranhão, W. Martins, S. Mauro, S. R. B. Medeiros, R. V. Meissner, M. A. Moreira, F. F. Nascimento, M. Nicolás, J. G. Oliveira, S. Oliveira, Roger F. C. Paixão, J. A. Parente, F. Pedrosa, Sergio Danilo Junho Penat, J. Pereira, M. Pereira, Luciana Santos Rodrigues Costa Pinto, Luciano Da SilvaPinto, J. Porto, D. P. Potrich, C. E. Ramalho-Neto, A. Reis, Liu U. Rigo, Edson Rondinelli, Elen Bethleen Pedraça do Santos, F. Santos, M. Schneider, H. Seuánez, Ana Maria Rodrigues da Silva, Artur Silva, D. W. Silva, Rosane Silva, I. C. Simões, Daniel Simon, C. M. Soares, and R. B. Soares. The complete genome sequence of chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability. Proceedings of the National Academy of Sciences of the United States of America, 100:11660-11665, Sep 2003. URL: https://doi.org/10.1073/pnas.1832124100, doi:10.1073/pnas.1832124100. This article has 398 citations and is from a highest quality peer-reviewed journal.
(vasconcelos2003thecompletegenome pages 3-4): A. Vasconcelos, D. F. Almeida, M. Hungria, C. T. Guimarães, R. Antônio, F. Almeida, L. G. Almeida, R. Almeida, J. Alves-Gomes, Elizabeth M. Mazoni Andrade, J. Araripe, Magnólia Araújo, S. Astolfi-Filho, V. Azevedo, A. J. Baptista, L. A. Bataus, J. Batista, A. Beló, C. Berg, M. Bogo, S. Bonatto, J. Bordignon, Marcelo M. Macedo Brigidom, C. Brito, M. Brocchi, H. A. Burity, A. Camargo, D. D. Cardoso, N. Carneiro, D. Carraro, C. Carvalho, J. Cascardo, B. Cavada, L. M. O. Chueire, T. Creczynski-Pasa, Nivaldo C. Costa Da Cunha-Junior, N. J. Fagundes, Clarissa Lima Falão, F. Fantinatti, I. Farias, M. Felipe, Lilian Pereira Ferrari, J. Ferro, M. Ferro, G. Franco, N. S. A. Freitas, L. R. Furlan, R. Gazzinelli, E. Gomes, P. Gonçalves, T. B. Grangeiro, D. Grattapaglia, E. Grisard, E. S. Hanna, S. N. Jardim, J. Laurino, Lélia Cristina Tenório Leoi, L. F. A. Lima, M. F. Loureiro, M. D. C. C. P. Lyra, H. Madeira, G. Manfio, A. Maranhão, W. Martins, S. Mauro, S. R. B. Medeiros, R. V. Meissner, M. A. Moreira, F. F. Nascimento, M. Nicolás, J. G. Oliveira, S. Oliveira, Roger F. C. Paixão, J. A. Parente, F. Pedrosa, Sergio Danilo Junho Penat, J. Pereira, M. Pereira, Luciana Santos Rodrigues Costa Pinto, Luciano Da SilvaPinto, J. Porto, D. P. Potrich, C. E. Ramalho-Neto, A. Reis, Liu U. Rigo, Edson Rondinelli, Elen Bethleen Pedraça do Santos, F. Santos, M. Schneider, H. Seuánez, Ana Maria Rodrigues da Silva, Artur Silva, D. W. Silva, Rosane Silva, I. C. Simões, Daniel Simon, C. M. Soares, and R. B. Soares. The complete genome sequence of chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability. Proceedings of the National Academy of Sciences of the United States of America, 100:11660-11665, Sep 2003. URL: https://doi.org/10.1073/pnas.1832124100, doi:10.1073/pnas.1832124100. This article has 398 citations and is from a highest quality peer-reviewed journal.
(nazaret2023marrfamilytranscriptional pages 1-2): Fanny Nazaret, Geneviève Alloing, Karine Mandon, and Pierre Frendo. Marr family transcriptional regulators and their roles in plant-interacting bacteria. Microorganisms, 11:1936, Jul 2023. URL: https://doi.org/10.3390/microorganisms11081936, doi:10.3390/microorganisms11081936. This article has 15 citations.
(beggs2020marrfamilyproteins pages 1-2): Grace A. Beggs, Richard G. Brennan, and Mehreen Arshad. Marr family proteins are important regulators of clinically relevant antibiotic resistance. Protein Science, 29:647-653, Nov 2020. URL: https://doi.org/10.1002/pro.3769, doi:10.1002/pro.3769. This article has 84 citations and is from a peer-reviewed journal.
(beggs2020marrfamilyproteins pages 2-4): Grace A. Beggs, Richard G. Brennan, and Mehreen Arshad. Marr family proteins are important regulators of clinically relevant antibiotic resistance. Protein Science, 29:647-653, Nov 2020. URL: https://doi.org/10.1002/pro.3769, doi:10.1002/pro.3769. This article has 84 citations and is from a peer-reviewed journal.
(nazaret2023marrfamilytranscriptional pages 2-4): Fanny Nazaret, Geneviève Alloing, Karine Mandon, and Pierre Frendo. Marr family transcriptional regulators and their roles in plant-interacting bacteria. Microorganisms, 11:1936, Jul 2023. URL: https://doi.org/10.3390/microorganisms11081936, doi:10.3390/microorganisms11081936. This article has 15 citations.
(nazaret2023marrfamilytranscriptional pages 4-6): Fanny Nazaret, Geneviève Alloing, Karine Mandon, and Pierre Frendo. Marr family transcriptional regulators and their roles in plant-interacting bacteria. Microorganisms, 11:1936, Jul 2023. URL: https://doi.org/10.3390/microorganisms11081936, doi:10.3390/microorganisms11081936. This article has 15 citations.
(previatomello2017globaltranscriptionalresponse pages 1-3): Maristela Previato-Mello, Diogo de Abreu Meireles, Luis Eduardo Soares Netto, and José Freire da Silva Neto. Global transcriptional response to organic hydroperoxide and the role of ohrr in the control of virulence traits in chromobacterium violaceum. Infection and Immunity, Aug 2017. URL: https://doi.org/10.1128/iai.00017-17, doi:10.1128/iai.00017-17. This article has 33 citations and is from a peer-reviewed journal.