Involved in the biosynthesis of the siderophore enterobactin (enterochelin), which is a macrocyclic trimeric lactone of N-(2,3-dihydroxybenzoyl)-serine. The serine trilactone serves as a scaffolding for the three catechol functionalities that provide hexadentate coordination for the tightly ligated iron(2+) atoms. EntE proccesses via a two-step adenylation-ligation reaction (bi-uni-uni-bi ping-pong mechanism). First, it catalyzes the activation of the carboxylate group of 2,3-dihydroxy-benzoate (DHB), via a reversible ATP-dependent pyrophosphate exchange reactions to yield the acyladenylate intermediate 2,3-dihydroxybenzoyl-AMP. It can also transfer AMP to salicylate, 2,4-dihydroxybenzoate, gentisate and 2,3,4-trihydroxybenzoate. In the second step, DHB is transferred from 2,3-dihydroxybenzoyl-AMP onto the phosphopantetheinylated EntB (holo-EntB) to form DHB-holo-EntB. Then this product will serve in the formation of the amide bond between 2,3-dihydroxybenzoate (DHB) and L-serine. 3 2,3-dihydroxybenzoate + 6 ATP + 3 L-serine = 6 AMP + 6 diphosphate + enterobactin + 4 H(+) 2,3-dihydroxybenzoate + ATP + holo-[aryl-carrier protein] = 2,3-dihydroxybenzoyl-[aryl-carrier protein] + AMP + diphosphate 2,3-dihydroxybenzoyl-5'-AMP + holo-[aryl-carrier protein] = 2,3-dihydroxybenzoyl-[aryl-carrier protein] + AMP + H(+) Siderophore biosynthesis; enterobactin biosynthesis. Proteins EntB, EntD, EntE, and EntF form a multienzyme complex called enterobactin synthase. Monomer. EntA and EntE interact together. Under conditions of iron deficiency and by the fur protein. Belongs to the ATP-dependent AMP-binding enzyme family. EntE subfamily.