NADP+ reduction with reduced ferredoxin and NADP+ reduction with NADH are coupled via an electron bifurcating enzyme complex in Clostridium kluyveri.
Summary of "NADP+ reduction with reduced ferredoxin and NADP+ reduction with NADH are coupled via an electron bifurcating enzyme complex in Clostridium kluyveri."
Recently it was found that the cytoplasmic butyryl-CoA dehydrogenase-EtfAB complex from Clostridium kluyveri couples the exergonic reduction of crotonyl-CoA to butyryl-CoA with NADH and the endergonic reduction of ferredoxin with NADH via flavin-based electron bifurcation. We report here on a second cytoplasmic enzyme complex in C. kluyveri capable of energetic coupling via this novel mechanism. It was found that the purified iron-sulfur flavoprotein complex NfnAB couples the exergonic reduction of NADP(+) with reduced ferredoxin and the endergonic reduction of NADP(+) with NADH in a reversible reaction: Fdred(2-) + NADH + 2 NADP(+) + H(+) = Fdox + NAD(+) + 2 NADPH. The role of this energy converting enzyme complex in the ethanol-acetate fermentation of the Clostridium is discussed.
Affiliation
Max Planck Institute for Terrestrial Microbiology, D-35043, Marburg, Germany.
Journal Details
This article was published in the following journal.
Name: Journal of bacteriology
ISSN: 1098-5530
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20675474
- DOI: http://dx.doi.org/10.1128/JB.00612-10
Medical and Biotech [MESH] Definitions
Ferredoxin-nadp Reductase
An enzyme that catalyzes the oxidation and reduction of FERREDOXIN or ADRENODOXIN in the presence of NADP. EC 1.18.1.2 was formerly listed as EC 1.6.7.1 and EC 1.6.99.4.
Nadp Transhydrogenase
An enzyme present in the mitochondrial membrane of animals and in microorganisms. In the presence of energy (ATP) it catalyzes reversibly the reduction of NAD by NADPH to yield NADP and NADH. This reaction permits the utilization of the reducing properties of NADPH by the respiratory chain and in the reverse direction it allows the reduction of NADP for biosynthetic purposes. EC 1.6.1.1.
Nadp
Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5'-phosphate (NMN) coupled by pyrophosphate linkage to the 5'-phosphate adenosine 2',5'-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed)
Dihydropteridine Reductase
An enzyme that catalyzes the reduction of 6,7-dihydropteridine to 5,6,7,8-tetrahydropteridine in the presence of NADP+. Defects in the enzyme are a cause of PHENYLKETONURIA II. Formerly listed as EC 1.6.99.7.
Valine Dehydrogenase (nadp+)
An amino acid oxidoreductase that catalyzes the oxidative hydroxylation of L-VALINE to 3-methyl-2-oxobutanoate and AMMONIA in the presence of NADP.
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