Characterization and X-ray structure of the NADH-dependent coenzyme A disulfide reductase from Thermus thermophilus

Andrea M. Lencina, Juergen Koepke, Julia Preu, Cornelia Muenke, Robert B. Gennis, Hartmut Michel, Lici A. Schurig-Briccio

Research output: Contribution to journalArticle

Abstract

The crystal structure of the enzyme previously characterized as a type-2 NADH:menaquinone oxidoreductase (NDH-2) from Thermus thermophilus has been solved at a resolution of 2.9 Å and revealed that this protein is, in fact, a coenzyme A-disulfide reductase (CoADR). Coenzyme A (CoASH) replaces glutathione as the major low molecular weight thiol in Thermus thermophilus and is maintained in the reduced state by this enzyme (CoADR). Although the enzyme does exhibit NADH:menadione oxidoreductase activity expected for NDH-2 enzymes, the specific activity with CoAD as an electron acceptor is about 5-fold higher than with menadione. Furthermore, the crystal structure contains coenzyme A covalently linked Cys44, a catalytic intermediate (Cys44-S-S-CoA) reduced by NADH via the FAD cofactor. Soaking the crystals with menadione shows that menadione can bind to a site near the redox active FAD, consistent with the observed NADH:menadione oxidoreductase activity. CoADRs from other species were also examined and shown to have measurable NADH:menadione oxidoreductase activity. Although a common feature of this family of enzymes, no biological relevance is proposed. The CoADR from T. thermophilus is a soluble homodimeric enzyme. Expression of the recombinant TtCoADR at high levels in E. coli results in a small fraction that co-purifies with the membrane fraction, which was used previously to isolate the enzyme wrongly identified as a membrane-bound NDH-2. It is concluded that T. thermophilus does not contain an authentic NDH-2 component in its aerobic respiratory chain.

Original languageEnglish (US)
Article number148080
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1860
Issue number11
DOIs
StatePublished - Nov 1 2019

Keywords

  • Coenzyme A disulfide reductase
  • Flavoprotein
  • NADH oxidation
  • Thermus thermophilus
  • X-ray structure

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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