Part of the multicomponent 3-phenylpropionate dioxygenase, that converts 3-phenylpropionic acid (PP) and cinnamic acid (CI) into 3-phenylpropionate-dihydrodiol (PP-dihydrodiol) and cinnamic acid-dihydrodiol (CI-dihydrodiol), respectively. H(+) + NAD(+) + 2 reduced [2Fe-2S]-[ferredoxin] = NADH + 2 oxidized [2Fe-2S]-[ferredoxin] Aromatic compound metabolism; 3-phenylpropanoate degradation. This dioxygenase system consists of four proteins: the two subunits of the hydroxylase component (HcaE and HcaF), a ferredoxin (HcaC) and a ferredoxin reductase (HcaD). Belongs to the bacterial ring-hydroxylating dioxygenase ferredoxin reductase family.