The FlxABCD-HdrABC proteins correspond to a novel NADH dehydrogenase/heterodisulfide reductase widespread in anaerobic bacteria and involved in ethanol metabolism in Desulfovibrio vulgarisHildenborough

Ana Raquel Ramos, Fabian Grein, Goncalo P. Oliveira, Sofia S. Venceslau, Kimberly L. Keller, Judy D. Wall, Ines A. C. Pereira

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Flavin-based electron bifurcation (FBEB) is an important mechanism for the energy metabolism of anaerobes. A new family of NADH dehydrogenases, the flavin oxidoreductase (FlxABCD, previously called FloxABCD), was proposed to perform FBEB in sulphate-reducing organisms coupled with heterodisulfide reductase (HdrABC). We found that the hdrABC-flxABCD gene cluster is widespread among anaerobic bacteria, pointing to a general and important role in their bioenergetics. In this work, we studied FlxABCD of Desulfovibrio vulgarisHildenborough. The hdr-flx genes are part of the same transcriptional unit and are increased in transcription during growth in ethanol-sulfate, and to a less extent during pyruvate fermentation. Two mutant strains were generated: one where expression of the hdr-flx genes was interrupted and another lacking the flxA gene. Both strains were unable to grow with ethanol-sulfate, whereas growth was restored in a flxA-complemented strain. The mutant strains also produced very reduced amounts of ethanol compared with the wild type during pyruvate fermentation. Our results show that in D.vulgaris, the FlxABCD-HdrABC proteins are essential for NADH oxidation during growth on ethanol, probably involving a FBEB mechanism that leads to reduction of ferredoxin and the small protein DsrC, while in fermentation they operate in reverse, reducing NAD(+) for ethanol production.

Original languageEnglish
Pages (from-to)2288-2305
Number of pages18
JournalEnvironmental Microbiology
Volume17
Issue number7
DOIs
Publication statusPublished - Jul 2015

Keywords

  • SULFATE-REDUCING BACTERIA
  • VULGARIS HILDENBOROUGH
  • METHANOGENIC ARCHAEA
  • ENERGY-METABOLISM
  • FORMATE DEHYDROGENASE
  • ALCOHOL-DEHYDROGENASE
  • CLOSTRIDIUM-KLUYVERI
  • ELECTRON BIFURCATION
  • COMPLEX
  • RESPIRATION

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