Characterization and X-ray structure of the NADH-dependent coenzyme A disulfide reductase from Thermus thermophilus
| Autor: | Hartmut Michel, Andrea M. Lencina, Lici A. Schurig-Briccio, Juergen Koepke, Cornelia Muenke, Julia Preu, Robert B. Gennis |
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| Rok vydání: | 2019 |
| Předmět: |
Models
Molecular Coenzyme A Static Electricity Biophysics Respiratory chain Reductase Biochemistry Cofactor 03 medical and health sciences chemistry.chemical_compound X-Ray Diffraction Menadione Oxidoreductase Escherichia coli NADH NADPH Oxidoreductases 030304 developmental biology chemistry.chemical_classification 0303 health sciences biology Chemistry Thermus thermophilus 030302 biochemistry & molecular biology Vitamin K 3 Cell Biology biology.organism_classification Recombinant Proteins Enzyme biology.protein |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1860:148080 |
| ISSN: | 0005-2728 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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