Regulation of the NADH and NADPH-ferredoxin oxidoreductases in clostridia of the butyric group.
NADH and NADPH-ferredoxin oxidoreductases have been studied in Clostridium acetobutylicum, Cl. tyrobutyricum and Cl. pasteurianum. The study of the distribution and regulation of these enzymatic activities in well-defined culture conditions, reveals that the essential function of NADPH-ferredoxin oxidoreductase is to produce NADPH, while NADH-ferredoxin oxidoreductase can, depending on cellular conditions, produce or oxidize NADH. When these Clostridia use glycolysis, regulation of the NADH-ferredoxin oxidoreductase by acetyl-CoA (obligatory activator of NADH-ferroxin reductase activity) and by NADH (competitive inhibitor of ferredoxin-NAD+ reductase activity) allow the enzymes to function correlatively with glyceraldehyde-3-phosphate dehydrogenase and thus control the levels of NAD+ and NADH in the cell. In Cl. tyrobutyricum and Cl. pasteurianum, the ferredoxin-NADP+ reductase  activities are regulated by NAD+ and NADH in accordance with the intracellular concentrations of these coenzymes. In Cl. tyrobutyricum growing on pyruvate/acetate, NADH and NADPH-ferredoxin reductase activities cannot be detected; only the ferredoxin-NAD+ and ferredoxin-NADP+ reductase activities are found. In this Clostridium, regulation of the ferredoxin-NADP+ reductase activity is the same whether it is grown on glucose or pyruvate. Contrary to this, the ferredoxin-NAD+ reductase activity undergoes a drastic change, since NADH no longer controls the enzymatic activity. In this case regulation is no longer necessary, since glyceraldehyde-3-phosphate dehydrogenase does not function.
D002087:Butyrates / Q000378:metabolism; D003013:Clostridium / Q000201:enzymology* / Q000378:metabolism; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D011773:Pyruvates / Q000378:metabolism; D013045:Species Specificity
D002087:Butyrates; D011773:Pyruvates; D009243:NAD; D009249:NADP; D005287:Ferredoxin-NADP Reductase; D009247:NADH, NADPH Oxidoreductases; D005947:Glucose