Ferredoxin NADP+ Reductase

OverviewOverview

Ferredoxin NADP⁺ Reductase zoomed in (4FK8)

<StructureSection load='4FK8' size='340' side='right' caption='FNR protein' scene=>

Ferredoxin NADP⁺ reductase [1] is an enzyme that catalyzes the reduction of NADP⁺ to NADPH. This enzyme belongs to a family of enzymes called oxidoreductases[2] that contain iron-sulfur proteins as electron donors and NAD⁺ or NADP⁺ as electron acceptors. FAD, [flavin adenine dinucleotide][3], is also a cofactor of FNR. The ferredoxin NADP⁺ reductase participates in a general reaction that proceeds as follows:

2 reduced ferredoxin + NADP⁺ ---> H⁺ + 2 oxidized ferredoxin + NADPH[4]

Anaerobic FunctionAnaerobic Function

In many facultatively anaerobic bacteria, FNR acts as an oxygen sensor modifying gene expression that adapts the cell to anaerobic growth. The activity of FNR regulates the cell's ability to metabolize aerobically or anaerobically so that when oxygen is abundant, FNR is destabilized and converted into an inactive form.

Structural highlightsStructural highlights

In its active form, the protein is a and contains a [4Fe-4S]⁺² cluster. When inactive, the protein is monomeric and containts a [3Fe-4S]⁺² cluster. FNR in its form can be seen here, with bound NADP and FAD.<ref> PMID: 21166900 <ref>