trpE

Anthranilate synthase component I (TrpE, locus PP_0417), the large alpha subunit of anthranilate synthase (EC 4.1.3.27). Together with the glutamine amidotransferase beta subunit TrpG, it forms a heterotetrameric complex that catalyzes the first committed step of L-tryptophan biosynthesis, the conversion of chorismate to anthranilate. TrpE binds chorismate and performs the amination/lyase chemistry, using ammonia supplied by TrpG from hydrolysis of L-glutamine; the products are anthranilate, pyruvate and L-glutamate. In the absence of TrpG, TrpE alone can produce anthranilate directly from chorismate when free ammonia is abundant. The enzyme requires Mg2+ and is a soluble, cytoplasmic enzyme of aromatic amino acid primary metabolism. Anthranilate synthase is typically feedback-inhibited by L-tryptophan, the pathway end product. In P. putida KT2440, loss of trpE causes tryptophan auxotrophy that is rescued by anthranilate, indole or tryptophan, confirming its placement at the anthranilate-forming step.