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

Biochim Biophys Acta Bioenerg. 2019 Nov 1;1860(11):148080. doi: 10.1016/j.bbabio.2019.148080. Epub 2019 Sep 11.


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.

Keywords: Coenzyme A disulfide reductase; Flavoprotein; NADH oxidation; Thermus thermophilus; X-ray structure.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Coenzyme A / chemistry
  • Coenzyme A / metabolism*
  • Escherichia coli
  • Models, Molecular
  • NADH, NADPH Oxidoreductases / chemistry*
  • NADH, NADPH Oxidoreductases / metabolism*
  • Recombinant Proteins
  • Static Electricity
  • Thermus thermophilus / enzymology*
  • Vitamin K 3 / chemistry
  • X-Ray Diffraction


  • Recombinant Proteins
  • coenzyme A disulfide
  • Vitamin K 3
  • NADH, NADPH Oxidoreductases
  • Coenzyme A