Component of two multicomponent enzyme systems which are involved in the catabolism of naphthalene (PubMed:9573207, PubMed:11872705). Plays a role as an electron transfer component for both salicylate 5-hydroxylase (S5H) and naphthalene 1,2-dioxygenase (NDO) systems, by transferring electrons from NAD(P)H to the oxygenase component via the ferredoxin NagAb (PubMed:9573207, PubMed:11872705). The electron transport chain from the two systems can use both NADH and NADPH as electron donors at approximately similar rates (PubMed:11872705). H(+) + NAD(+) + 2 reduced [2Fe-2S]-[ferredoxin] = NADH + 2 oxidized [2Fe-2S]-[ferredoxin] H(+) + NADP(+) + 2 reduced [2Fe-2S]-[ferredoxin] = NADPH + 2 oxidized [2Fe-2S]-[ferredoxin] Binds 1 [2Fe-2S] cluster. Aromatic compound metabolism; naphthalene degradation. Ferredoxin reductase NagAa belongs to both the salicylate 5-hydroxylase (S5H) and the naphthalene 1,2-dioxygenase (NDO) multicomponent enzyme systems. The NDO multicomponent enzyme system is composed of an electron transfer component and a dioxygenase component (iron sulfur protein (ISP)). The electron transfer component is composed of a ferredoxin reductase (NagAa) and a ferredoxin (NagAb), and the dioxygenase component is formed by a large alpha subunit (NagAc) and a small beta subunit (NagAd). The S5H multicomponent enzyme system is composed of an electron transfer component and a monooxygenase component. The electron transfer component is comprised of a ferredoxin reductase (NagAa) and a ferredoxin (NagAb), and the monooxygenase component is formed by a large subunit (NagG) and a small subunit (NagH). Belongs to the bacterial ring-hydroxylating dioxygenase ferredoxin reductase family.