{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T00:05:19Z","timestamp":1773273919646,"version":"3.50.1"},"reference-count":43,"publisher":"American Society for Microbiology","issue":"13","license":[{"start":{"date-parts":[[2007,7,1]],"date-time":"2007-07-01T00:00:00Z","timestamp":1183248000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["J Bacteriol"],"published-print":{"date-parts":[[2007,7]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n          <jats:p>\n            Pyruvate-dependent reduction of NADP has been demonstrated in cell extracts of the human gastric pathogen\n            <jats:italic>Helicobacter pylori.<\/jats:italic>\n            However, NADP is not a substrate of purified pyruvate:ferredoxin oxidoreductase (PFOR), suggesting that other redox active enzymes mediate this reaction. Here we show that\n            <jats:italic>fqrB<\/jats:italic>\n            (HP1164), which is essential and highly conserved among the epsilonproteobacteria, exhibits NADPH oxidoreductase activity. FqrB was purified by nickel interaction chromatography following overexpression in\n            <jats:italic>Escherichia coli<\/jats:italic>\n            . The protein contained flavin adenine dinucleotide and exhibited NADPH quinone reductase activity with menadione or benzoquinone and weak activity with cytochrome\n            <jats:italic>c<\/jats:italic>\n            , molecular oxygen, and 5,5\u2032-dithio-bis-2-nitrobenzoic acid (DTNB). FqrB exhibited a ping-pong catalytic mechanism, a\n            <jats:italic>k<\/jats:italic>\n            <jats:sub>cat<\/jats:sub>\n            of 122 s\n            <jats:sup>\u22121<\/jats:sup>\n            , and an apparent\n            <jats:italic>\n              K\n              <jats:sub>m<\/jats:sub>\n            <\/jats:italic>\n            of 14 \u03bcM for menadione and 26 \u03bcM for NADPH. FqrB also reduced flavodoxin (FldA), the electron carrier of PFOR. In coupled enzyme assays with purified PFOR and FldA, FqrB reduced NADP in a pyruvate- and reduced coenzyme A (CoA)-dependent manner. Moreover, in the presence of NADPH, CO\n            <jats:sub>2<\/jats:sub>\n            , and acetyl-CoA, the PFOR:FldA:FqrB complex generated pyruvate via CO\n            <jats:sub>2<\/jats:sub>\n            fixation. PFOR was the rate-limiting enzyme in the complex, and nitazoxanide, a specific inhibitor of PFOR of\n            <jats:italic>H. pylori<\/jats:italic>\n            and\n            <jats:italic>Campylobacter jejuni<\/jats:italic>\n            , also inhibited NADP reduction in cell-free lysates. These capnophilic (CO\n            <jats:sub>2<\/jats:sub>\n            -requiring) organisms contain gaps in pathways of central metabolism that would benefit substantially from pyruvate formation via CO\n            <jats:sub>2<\/jats:sub>\n            fixation. Thus, FqrB provides a novel function in pyruvate metabolism and, together with production of superoxide anions via quinone reduction under high oxygen tensions, contributes to the unique microaerobic lifestyle that defines the epsilonproteobacterial group.\n          <\/jats:p>","DOI":"10.1128\/jb.00287-07","type":"journal-article","created":{"date-parts":[[2007,4,28]],"date-time":"2007-04-28T00:40:00Z","timestamp":1177720800000},"page":"4764-4773","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":58,"title":["Flavodoxin:Quinone Reductase (FqrB): a Redox Partner of Pyruvate:Ferredoxin Oxidoreductase That Reversibly Couples Pyruvate Oxidation to NADPH Production in\n            <i>Helicobacter pylori<\/i>\n            and\n            <i>Campylobacter jejuni<\/i>"],"prefix":"10.1128","volume":"189","author":[{"given":"Martin","family":"St. Maurice","sequence":"first","affiliation":[{"name":"Department of Microbiology and Immunology"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nunilo","family":"Cremades","sequence":"additional","affiliation":[{"name":"Departamento de Bioqui\u0301mica y Biologi\u0301a Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza"},{"name":"Biocomputing and Physics of Complex Systems Institute, Zaragoza Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Matthew A.","family":"Croxen","sequence":"additional","affiliation":[{"name":"Department of Medicine, Division of Infectious Diseases and International Health"},{"name":"Department of Microbiology, University of Virginia, Charlottesville, Virginia 22908"},{"name":"Department of Microbiology and Immunology"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gary","family":"Sisson","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Immunology"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Javier","family":"Sancho","sequence":"additional","affiliation":[{"name":"Departamento de Bioqui\u0301mica y Biologi\u0301a Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza"},{"name":"Biocomputing and Physics of Complex Systems Institute, Zaragoza Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Paul S.","family":"Hoffman","sequence":"additional","affiliation":[{"name":"Department of Medicine, Division of Infectious Diseases and International Health"},{"name":"Department of Microbiology, University of Virginia, Charlottesville, Virginia 22908"},{"name":"Department of Microbiology and Immunology"},{"name":"Department of Medicine, Division of Infectious Diseases, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1038\/16513","volume":"397","year":"1999","unstructured":"Alm, R. 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