title: Inhibition of the sodium-translocating NADH-ubiquinone oxidoreductase [Na+-NQR] decreases cholera toxin production in Vibrio cholerae O1 at the late exponential growth phase.
abstract: Two virulence factors produced by Vibrio cholerae, cholera toxin (CT) and toxin-corregulated pilus (TCP), are indispensable for cholera infection. ToxT is the central regulatory protein involved in activation of CT and TCP expression. We previously reported that lack of a respiration-linked sodium-translocating NADH-ubiquinone oxidoreductase (Na(+)-NQR) significantly increases toxT transcription. In this study, we further characterized this link and found that Na(+)-NQR affects toxT expression only at the early-log growth phase, whereas lack of Na(+)-NQR decreases CT production after the mid-log growth phase. Such decreased CT production was independent of toxT and ctxB transcription. Supplementing a respiratory substrate, l-lactate, into the growth media restored CT production in the nqrA-F mutant, suggesting that decreased CT production in the Na(+)-NQR mutant is dependent on electron transport chain (ETC) activity. This notion was supported by the observations that two chemical inhibitors, a Na(+)-NQR specific inhibitor 2-n-Heptyl-4-hydroxyquinoline N-oxide (HQNO) and a succinate dehydrogenase (SDH) inhibitor, thenoyltrifluoroacetone (TTFA), strongly inhibited CT production in both classical and El Tor biotype strains of V. cholerae. Accordingly, we propose the main respiratory enzyme of V. cholerae, as a potential drug target to treat cholera because human mitochondria do not contain Na(+)-NQR orthologs.
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Minato
authors.affiliation: Department of Microbiology, College of Science, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Sara R
authors.initials: SR
authors.lastname: Fassio
authors.affiliation: Department of Microbiology, College of Science, Oregon State University, Corvallis, OR 97331, USA; Molecular and Cellular Biology Graduate Program, College of Science, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Rylan L
authors.initials: RL
authors.lastname: Reddekopp
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA; Department of Microbiology, College of Science, Oregon State University, Corvallis, OR 97331, USA; Molecular and Cellular Biology Graduate Program, College of Science, Oregon State University, Corvallis, OR 97331, USA. Electronic address: hasec@science.oregonstate.edu.
authors.forename: Claudia C
authors.initials: CC
authors.lastname: Häse
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002772:Cholera Toxin / Q000096:biosynthesis*; D042967:Electron Transport Complex I / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006912:Hydroxyquinolines / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013804:Thenoyltrifluoroacetone / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D041241:Vibrio cholerae O1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006912:Hydroxyquinolines; D014157:Transcription Factors; D037521:Virulence Factors; C075626:tcpN protein, Vibrio cholerae; C001333:2-(n-heptyl)-4-hydroxyquinoline N-oxide; D013804:Thenoyltrifluoroacetone; D002772:Cholera Toxin; D012964:Sodium; D013385:Succinate Dehydrogenase; D042967:Electron Transport Complex I
keywords: Anti-virulence drug; Cholera toxin; Electron transport chain; Na(+)-NQR; Vibrio cholerae