{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T06:08:14Z","timestamp":1771481294136,"version":"3.50.1"},"reference-count":48,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,2,17]],"date-time":"2026-02-17T00:00:00Z","timestamp":1771286400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Secretary of Science, Humanities, Technology and Innovation","award":["A-1S-27116"],"award-info":[{"award-number":["A-1S-27116"]}]},{"name":"Secretary of Science, Humanities, Technology and Innovation","award":["CBF2023-2024-708"],"award-info":[{"award-number":["CBF2023-2024-708"]}]},{"DOI":"10.13039\/501100006054","name":"University of Guanajuato","doi-asserted-by":"crossref","award":["CIIC-029-2024"],"award-info":[{"award-number":["CIIC-029-2024"]}],"id":[{"id":"10.13039\/501100006054","id-type":"DOI","asserted-by":"crossref"}]},{"name":"SECIHTI"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>ywqN encodes a protein with an unassigned function that shares partial 3D homology with B. subtilis YhdA, Pseudomonas putida ChrR, and Escherichia coli YieF, which are NADP(H)\/FMN-dependent oxidoreductases that catalyze the reduction of diverse chemical pollutants, including Cr(VI). Here, we report that a recombinant His6-YwqN protein displays marginal chromate reductase activity but is capable of reducing synthetic azo dyes. Remarkably, His6-YwqN exhibits a potent quinone reductase activity, catalyzing the reduction of menadione (MD) and 1,4-naphthoquinone (NQ). The individual and combined roles of YwqN and YhdA in protecting B. subtilis from ROS-promoting agents were further tested. Sensitization to the oxidizing agent H2O2 required the simultaneous loss of both YwqN and YhdA. In contrast, strains deficient in ywqN, either alone or in combination with yhdA, exhibited similar but higher susceptibilities to the superoxide-generating agent MD compared with the WT strain. These results indicate that YwqN and YhdA contribute to protection against the deleterious effects of ROS in B. subtilis. Further results revealed that while YwqN, but not YhdA, prevented MD-induced mutagenesis, both proteins synergistically prevented RifR mutations induced by H2O2. Furthermore, overexpression of YwqN suppressed the hypermutagenesis phenotype of a B. subtilis strain deficient in the prevention\/repair oxidized guanine (GO) system, which is prone to accumulate 8-oxoGs. In summary, YwqN counteracts the cytotoxic and genotoxic effects promoted by ROS in B. subtilis and represents a potential tool for the remediation of soils and effluents contaminated with carcinogenic azo dyes.<\/jats:p>","DOI":"10.3390\/molecules31040701","type":"journal-article","created":{"date-parts":[[2026,2,17]],"date-time":"2026-02-17T13:15:35Z","timestamp":1771334135000},"page":"701","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Potent Quinone Reductase Encoded by ywqN (Qnr1) Protects Bacillus subtilis from Oxygen Radical Genotoxicity"],"prefix":"10.3390","volume":"31","author":[{"given":"Beatriz R.","family":"Gonz\u00e1lez","sequence":"first","affiliation":[{"name":"Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato C.P. 36060, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Norma","family":"Ram\u00edrez","sequence":"additional","affiliation":[{"name":"Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato C.P. 36060, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-4120-140X","authenticated-orcid":false,"given":"Karen","family":"Abundiz-Y\u00e1\u00f1ez","sequence":"additional","affiliation":[{"name":"Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato C.P. 36060, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4629-9645","authenticated-orcid":false,"given":"V\u00edctor M.","family":"Ayala-Garc\u00eda","sequence":"additional","affiliation":[{"name":"Faculty of Chemical Sciences, Juarez University of Durango State, Av. Veterinaria S\/N. Circuito Universitario. Col. Valle del Sur, Durango C.P. 34120, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5825-9766","authenticated-orcid":false,"given":"Luz I.","family":"Valenzuela-Garc\u00eda","sequence":"additional","affiliation":[{"name":"Department of Sustainable Engineering, Advanced Materials Research Center (CIMAV), Arroyo Seco, Durango C.P. 34147, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3957-7101","authenticated-orcid":false,"given":"Eduardo A.","family":"Robleto","sequence":"additional","affiliation":[{"name":"School of Life Sciences, University of Nevada, Las Vegas, NV 89154, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mario","family":"Pedraza-Reyes","sequence":"additional","affiliation":[{"name":"Department of Biology, Division of Natural and Exact Sciences, University of Guanajuato, Guanajuato C.P. 36060, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1016\/j.bbapap.2017.11.005","article-title":"Review of NAD(P)H-dependent oxidoreductases: Properties, engineering and application","volume":"1866","author":"Vidal","year":"2018","journal-title":"Biochim. Biophys. Acta (BBA)\u2014Proteins Proteom."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3942","DOI":"10.1111\/j.1742-4658.2009.07122.x","article-title":"Structural and mechanistic aspects of flavoproteins: Photosynthetic electron transfer from photosystem I to NADP+","volume":"276","author":"Medina","year":"2009","journal-title":"FEBS J."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"3965","DOI":"10.1007\/s00253-019-09775-2","article-title":"Remarkable diversification of bacterial azoreductases: Primary sequences, structures, substrates, physiological roles, and biotechnological applications","volume":"103","author":"Suzuki","year":"2019","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"568","DOI":"10.2741\/e400","article-title":"Toxicological significance of azo dye metabolism by human intestinal microbiota","volume":"E4","author":"Chen","year":"2012","journal-title":"Front. Biosci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1007\/s00018-007-7300-y","article-title":"Flavin-dependent quinone reductases","volume":"65","author":"Deller","year":"2008","journal-title":"Cell. Mol. Life Sci."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Ryan, A., Kaplan, E., Nebel, J.-C., Polycarpou, E., Crescente, V., Lowe, E., Preston, G.M., and Sim, E. (2014). Identification of NAD(P)H Quinone Oxidoreductase Activity in Azoreductases from P. aeruginosa: Azoreductases and NAD(P)H Quinone Oxidoreductases Belong to the Same FMN-Dependent Superfamily of Enzymes. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0098551"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"e01688-20","DOI":"10.1128\/AEM.01688-20","article-title":"Novel Biochemical Properties and Physiological Role of the Flavin Mononucleotide Oxidoreductase YhdA from Bacillus subtilis","volume":"86","author":"Zapata","year":"2020","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"22590","DOI":"10.1074\/jbc.M501654200","article-title":"ChrR, a Soluble Quinone Reductase of Pseudomonas putida That Defends against H2O2","volume":"280","author":"Gonzalez","year":"2005","journal-title":"J. Biol. Chem."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1016\/j.abb.2010.03.019","article-title":"NAD(P)H:quinone acceptor oxidoreductase 1 (NQO1), a multifunctional antioxidant enzyme and exceptionally versatile cytoprotector","volume":"501","author":"Talalay","year":"2010","journal-title":"Arch. Biochem. Biophys."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"873","DOI":"10.1128\/AEM.70.2.873-882.2004","article-title":"Chromate-Reducing Properties of Soluble Flavoproteins from Pseudomonas putida and Escherichia coli","volume":"70","author":"Ackerley","year":"2004","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"3371","DOI":"10.1128\/JB.188.9.3371-3381.2006","article-title":"Effect of Chromate Stress on Escherichia coli K-12","volume":"188","author":"Ackerley","year":"2006","journal-title":"J. Bacteriol."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Eswaramoorthy, S., Poulain, S., Hienerwadel, R., Bremond, N., Sylvester, M.D., Zhang, Y.-B., Berthomieu, C., Van Der Lelie, D., and Matin, A. (2012). Crystal Structure of ChrR\u2014A Quinone Reductase with the Capacity to Reduce Chromate. PLoS ONE, 7.","DOI":"10.1371\/journal.pone.0036017"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"D654","DOI":"10.1093\/nar\/gkv1006","article-title":"Subti Wiki 2.0\u2014An integrated database for the model organism Bacillus subtilis","volume":"44","author":"Michna","year":"2016","journal-title":"Nucleic Acids Res."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"D564","DOI":"10.1093\/nar\/gkae1091","article-title":"Updated resources for exploring experimentally-determined PDB structures and Computed Structure Models at the RCSB Protein Data Bank","volume":"53","author":"Burley","year":"2025","journal-title":"Nucleic Acids Res."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"3784","DOI":"10.1093\/nar\/gkg563","article-title":"ExPASy: The proteomics server for in-depth protein knowledge and analysis","volume":"31","author":"Gasteiger","year":"2003","journal-title":"Nucleic Acids Res."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"20960","DOI":"10.1074\/jbc.273.33.20960","article-title":"Biochemical Characterization of WrbA, Founding Member of a New Family of Multimeric Flavodoxin-like Proteins","volume":"273","author":"Grandori","year":"1998","journal-title":"J. Biol. Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1016\/0041-008X(92)90273-U","article-title":"Quinone chemistry and toxicity","volume":"112","author":"Monks","year":"1992","journal-title":"Toxicol. Appl. Pharmacol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"6471","DOI":"10.1038\/srep06471","article-title":"Sequence-motif Detection of NAD(P)-binding Proteins: Discovery of a Unique Antibacterial Drug Target","volume":"4","author":"Hua","year":"2014","journal-title":"Sci. Rep."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"549","DOI":"10.1042\/BJ20150856","article-title":"Identification of novel members of the bacterial azoreductase family in Pseudomonas aeruginosa","volume":"473","author":"Crescente","year":"2016","journal-title":"Biochem. J."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3004","DOI":"10.1110\/ps.051680805","article-title":"Crystal structures of the tryptophan repressor binding protein WrbA and complexes with flavin mononucleotide","volume":"14","author":"Gorman","year":"2005","journal-title":"Protein Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"543","DOI":"10.1021\/bi061769c","article-title":"Role of Flavin Mononucleotide in the Thermostability and Oligomerization of Escherichia coli Stress-Defense Protein WrbA","volume":"46","author":"Natalello","year":"2007","journal-title":"Biochemistry"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e1581","DOI":"10.21769\/BioProtoc.1581","article-title":"Determination of Quinone Reductase Activity","volume":"5","author":"Mancini","year":"2015","journal-title":"Bio-Protocol"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"9518","DOI":"10.1074\/jbc.275.13.9518","article-title":"Dissecting the Energetics of the Apoflavodoxin-FMN Complex","volume":"275","author":"Lostao","year":"2000","journal-title":"J. Biol. Chem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"813","DOI":"10.1016\/S0300-9084(00)88876-8","article-title":"Apoflavodoxin: Structure, stability, and FMN binding","volume":"80","author":"Maldonado","year":"1998","journal-title":"Biochemistry"},{"key":"ref_25","unstructured":"Berg, J.M., Tymoczko, J.L., Stryer, L., and Stryer, L. (2002). Biochemistry, W.H. Freeman. [5th ed.]."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2556","DOI":"10.1021\/acs.jchemed.1c01268","article-title":"Visual Interpretation of the Meaning of kcat\/KM in Enzyme Kinetics","volume":"99","author":"Park","year":"2022","journal-title":"J. Chem. Educ."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1111\/j.1574-6968.2004.tb09638.x","article-title":"Expression and characteristics of the gene encoding azoreductase from Rhodobacter sphaeroides AS1.1737","volume":"236","author":"Bin","year":"2004","journal-title":"FEMS Microbiol. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.pep.2003.12.016","article-title":"Molecular cloning, overexpression, purification, and characterization of an aerobic FMN-dependent azoreductase from Enterococcus faecalis","volume":"34","author":"Chen","year":"2004","journal-title":"Protein Expr. Purif."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1433","DOI":"10.1099\/mic.0.27805-0","article-title":"Biochemical and molecular characterization of an azoreductase from Staphylococcus aureus, a tetrameric NADPH-dependent flavoprotein","volume":"151","author":"Chen","year":"2005","journal-title":"Microbiology"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"7083","DOI":"10.1021\/bi052478r","article-title":"Characterization of a Thermostable NADPH:FMN Oxidoreductase from the Mesophilic Bacterium Bacillus subtilis","volume":"45","author":"Deller","year":"2006","journal-title":"Biochemistry"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1016\/j.abb.2007.03.003","article-title":"Crystal structure of an aerobic FMN-dependent azoreductase (AzoA) from Enterococcus faecalis","volume":"463","author":"Liu","year":"2007","journal-title":"Arch. Biochem. Biophys."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"46394","DOI":"10.1074\/jbc.M104483200","article-title":"Putative ACP Phosphodiesterase Gene (acpD) Encodes an Azoreductase","volume":"276","author":"Nakanishi","year":"2001","journal-title":"J. Biol. Chem."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"10646","DOI":"10.1021\/acs.est.0c02521","article-title":"Electron Hopping Enables Rapid Electron Transfer between Quinone-\/Hydroquinone-Containing Organic Molecules in Microbial Iron(III) Mineral Reduction","volume":"54","author":"Bai","year":"2020","journal-title":"Environ. Sci. Technol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"222","DOI":"10.1016\/j.tox.2008.01.017","article-title":"Hexavalent chromium causes the oxidation of thioredoxin in human bronchial epithelial cells","volume":"246","author":"Myers","year":"2008","journal-title":"Toxicology"},{"key":"ref_35","first-page":"1","article-title":"Molecular mechanisms of quinone cytotoxicity","volume":"80","year":"1991","journal-title":"Chem. Biol. Interact."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"e00158-23","DOI":"10.1128\/mmbr.00158-23","article-title":"Bacillus subtilis stress-associated mutagenesis and developmental DNA repair","volume":"88","author":"Robleto","year":"2024","journal-title":"Microbiol. Mol. Biol. Rev."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"126","DOI":"10.1016\/j.freeradbiomed.2015.07.150","article-title":"In cellulo monitoring of quinone reductase activity and reactive oxygen species production during the redox cycling of 1,2 and 1,4 quinones","volume":"89","author":"Cassagnes","year":"2015","journal-title":"Free Radic. Biol. Med."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1007\/s00253-008-1555-6","article-title":"Enhancing survival of Escherichia coli by expression of azoreductase AZR possessing quinone reductase activity","volume":"80","author":"Liu","year":"2008","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"847","DOI":"10.1111\/j.1365-2958.2006.05302.x","article-title":"The diverse antioxidant systems of Helicobacter pylori","volume":"61","author":"Wang","year":"2006","journal-title":"Mol. Microbiol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1391","DOI":"10.1128\/IAI.72.3.1391-1396.2004","article-title":"An NADPH Quinone Reductase of Helicobacter pylori Plays an Important Role in Oxidative Stress Resistance and Host Colonization","volume":"72","author":"Wang","year":"2004","journal-title":"Infect. Immun."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"5493","DOI":"10.1128\/AEM.01665-14","article-title":"Role of Bacillus subtilis Error Prevention Oxidized Guanine System in Counteracting Hexavalent Chromium-Promoted Oxidative DNA Damage","volume":"80","year":"2014","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1128\/jb.110.1.281-290.1972","article-title":"Regulation of the Bacterial Cell Wall: Analysis of a Mutant of Bacillus subtilis Defective in Biosynthesis of Teichoic Acid","volume":"110","author":"Boylan","year":"1972","journal-title":"J. Bacteriol."},{"key":"ref_43","unstructured":"Sambrook, J., Fritsch, E.F., and Maniatis, T. (1989). Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press. [2nd. ed.]."},{"key":"ref_44","unstructured":"Harwood, C.R., and Cutting, S.M. (1990). Molecular Biological Methods for Bacillus, Wiley."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"680","DOI":"10.1038\/227680a0","article-title":"Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4","volume":"227","author":"Laemmli","year":"1970","journal-title":"Nature"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"W13","DOI":"10.1093\/nar\/gkr245","article-title":"T-Coffee: A web server for the multiple sequence alignment of protein and RNA sequences using structural information and homology extension","volume":"39","author":"Moretti","year":"2011","journal-title":"Nucleic Acids Res."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"De Azevedo, W.F. (2019). Molegro Virtual Docker for Docking. Docking Screens for Drug Discovery, Springer.","DOI":"10.1007\/978-1-4939-9752-7"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"W530","DOI":"10.1093\/nar\/gkab294","article-title":"PLIP 2021, expanding the scope of the protein\u2013ligand interaction profiler to DNA and RNA","volume":"49","author":"Adasme","year":"2021","journal-title":"Nucleic Acids Res."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/4\/701\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T05:13:29Z","timestamp":1771478009000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/4\/701"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,17]]},"references-count":48,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["molecules31040701"],"URL":"https:\/\/doi.org\/10.3390\/molecules31040701","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,17]]}}}