  1.6.1.4 | metabolism |
the enzyme has a key role in maintaining redox homeostasis. It is involved in maintaining the cellular redox balance, producing NADPH for biosynthesis by recycling the two other primary redox carriers, NADH and ferredoxin. The enzyme effectively couples the endergonic reduction of NADP+ by NADH and the exergonic reduction of NADP+ by reduced ferredoxin, thereby maintaining a high ratio of NADPH/NADP+ to drive biosynthesis. The Pyrococcus furiosus genome encodes an NfnI paralog termed NfnII, and the two are differentially expressed, depending on the growth conditions. Deletion of the genes encoding either NfnI or NfnII affects the cellular concentrations of NAD(P)H and particularly NADPH. This results in a moderate to severe growth phenotype in deletion mutants, demonstrating a key role for each enzyme in maintaining redox homeostasis |
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