Carnitine metabolism to trimethylamine by an unusual Rieske-type oxygenase from human microbiota

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Dangosydd eitem ddigidol (DOI)

  • Yijun Zhu
    The University of Warwick
  • Eleanor Jameson
    University of Warwick
  • Marialuisa Crosatti
    University of Leicester
  • Hendrik Schäfer
    University of Warwick
  • Kumar Rajakumar
    University of Leicester
  • Timothy D H Bugg
    University of Warwick
  • Yin Chen
    University of Warwick

Dietary intake of L-carnitine can promote cardiovascular diseases in humans through microbial production of trimethylamine (TMA) and its subsequent oxidation to trimethylamine N-oxide by hepatic flavin-containing monooxygenases. Although our microbiota are responsible for TMA formation from carnitine, the underpinning molecular and biochemical mechanisms remain unclear. In this study, using bioinformatics approaches, we first identified a two-component Rieske-type oxygenase/reductase (CntAB) and associated gene cluster proposed to be involved in carnitine metabolism in representative genomes of the human microbiota. CntA belongs to a group of previously uncharacterized Rieske-type proteins and has an unusual "bridging" glutamate but not the aspartate residue, which is believed to facilitate intersubunit electron transfer between the Rieske center and the catalytic mononuclear iron center. Using Acinetobacter baumannii as the model, we then demonstrate that cntAB is essential in carnitine degradation to TMA. Heterologous overexpression of cntAB enables Escherichia coli to produce TMA, confirming that these genes are sufficient in TMA formation. Site-directed mutagenesis experiments have confirmed that this unusual "bridging glutamate" residue in CntA is essential in catalysis and neither mutant (E205D, E205A) is able to produce TMA. Taken together, the data in our study reveal the molecular and biochemical mechanisms underpinning carnitine metabolism to TMA in human microbiota and assign the role of this novel group of Rieske-type proteins in microbial carnitine metabolism.

Allweddeiriau

Iaith wreiddiolSaesneg
Tudalennau (o-i)4268-73
Nifer y tudalennau6
CyfnodolynProceedings of the National Academy of Sciences of the United States of America
Cyfrol111
Rhif y cyfnodolyn11
Dyddiad ar-lein cynnar3 Maw 2014
Dynodwyr Gwrthrych Digidol (DOIs)
StatwsCyhoeddwyd - 18 Maw 2014
Cyhoeddwyd yn allanolIe
Gweld graff cysylltiadau