Back to Search
Start Over
Insights into Flavin-based Electron Bifurcation via the NADH-dependent Reduced Ferredoxin:NADP Oxidoreductase Structure.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2015 Sep 04; Vol. 290 (36), pp. 21985-95. Date of Electronic Publication: 2015 Jul 02. - Publication Year :
- 2015
-
Abstract
- NADH-dependent reduced ferredoxin:NADP oxidoreductase (NfnAB) is found in the cytoplasm of various anaerobic bacteria and archaea. The enzyme reversibly catalyzes the endergonic reduction of ferredoxin with NADPH driven by the exergonic transhydrogenation from NADPH onto NAD(+). Coupling is most probably accomplished via the mechanism of flavin-based electron bifurcation. To understand this process on a structural basis, we heterologously produced the NfnAB complex of Thermotoga maritima in Escherichia coli, provided kinetic evidence for its bifurcating behavior, and determined its x-ray structure in the absence and presence of NADH. The structure of NfnAB reveals an electron transfer route including the FAD (a-FAD), the [2Fe-2S] cluster of NfnA and the FAD (b-FAD), and the two [4Fe-4S] clusters of NfnB. Ferredoxin is presumably docked onto NfnB close to the [4Fe-4S] cluster distal to b-FAD. NAD(H) binds to a-FAD and NADP(H) consequently to b-FAD, which is positioned in the center of the NfnAB complex and the site of electron bifurcation. Arg(187) is hydrogen-bonded to N5 and O4 of the bifurcating b-FAD and might play a key role in adjusting a low redox potential of the FADH(•)/FAD pair required for ferredoxin reduction. A mechanism of FAD-coupled electron bifurcation by NfnAB is proposed.<br /> (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Subjects :
- Bacterial Proteins chemistry
Bacterial Proteins genetics
Binding Sites
Crystallography, X-Ray
Electron Transport
Electrons
Electrophoresis, Polyacrylamide Gel
Ferredoxin-NADP Reductase chemistry
Ferredoxin-NADP Reductase genetics
Ferredoxins chemistry
Ferredoxins metabolism
Flavins chemistry
Hydrogen Bonding
Iron-Sulfur Proteins chemistry
Iron-Sulfur Proteins metabolism
Models, Molecular
Multiprotein Complexes chemistry
Multiprotein Complexes metabolism
NAD chemistry
Oxidation-Reduction
Protein Binding
Protein Structure, Tertiary
Recombinant Proteins chemistry
Recombinant Proteins metabolism
Substrate Specificity
Thermotoga maritima enzymology
Thermotoga maritima genetics
Bacterial Proteins metabolism
Ferredoxin-NADP Reductase metabolism
Flavins metabolism
NAD metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 290
- Issue :
- 36
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 26139605
- Full Text :
- https://doi.org/10.1074/jbc.M115.656520