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. This protein seems to be a 2Fe-2S ferredoxin (By similarity). Binds 1 [2Fe-2S] cluster per subunit. 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 component family.