pheA encodes a bifunctional chorismate mutase/prephenate dehydratase, a key enzyme in the L-phenylalanine biosynthesis pathway that is subject to feedback inhibition by L-phenylalanine. A truncated feedback-resistant variant, pheAfbr, lacking the regulatory R-domain, retains native catalytic activity and thermostability while relieving feedback inhibition. Overexpression of this variant is commonly employed to increase phenylpyruvate production from glucose [350].
The chorismate mutase domain of pheA (pheACM) is catalytically active as an independent unit and has been overexpressed to increase chorismate availability for metabolic pathways other than phenylalanine biosynthesis [343].