Involved in the biosynthesis of the siderophore enterobactin (enterochelin), which is a macrocyclic trimeric lactone of N-(2,3-dihydroxybenzoyl)-serine (PubMed:216414, PubMed:1826089, PubMed:1338974, PubMed:9485415). EntF catalyzes the activation of L-serine via ATP-dependent PPi exchange reaction to form seryladenylate (PubMed:1826089, PubMed:1338974, PubMed:9485415, PubMed:10688898). Activated L-serine is loaded onto the peptidyl carrier domain via a thioester linkage to the phosphopanthetheine moiety, forming seryl-S-Ppant-EntF (PubMed:9485415). EntF acts then as the sole catalyst for the formation of the three amide and three ester linkages found in enterobactin, using seryladenylate and 2,3-dihydroxybenzoate-S-Ppant-EntB (DHB-S-Ppant-EntB) as substrates, via the formation of a DHB-Ser-S-Ppant-EntF intermediate (PubMed:9485415). 3 2,3-dihydroxybenzoate + 6 ATP + 3 L-serine = 6 AMP + 6 diphosphate + enterobactin + 4 H(+) ATP + holo-[peptidyl-carrier protein] + L-serine = AMP + diphosphate + L-seryl-[peptidyl-carrier protein] Binds 1 phosphopantetheine covalently. Adenylation activity is increased in the presence of the MbtH-like protein YbdZ. kcat is 760 min(-1) with L-serine as substrate. kcat is 660 min(-1) with ATP as substrate. kcat is 720 min(-1) with O-acetyl-L-serine as substrate. kcat is 870 min(-1) with L-beta-chloroalanine as substrate. kcat is 38 min(-1) with S-methyl-L-cysteine as substrate. Siderophore biosynthesis; enterobactin biosynthesis. Proteins EntB, EntD, EntE and EntF are the component of the enterobactin synthase (PubMed:216414, PubMed:9485415). Components probably do not form a stable complex (PubMed:9485415). EntF acts as a catalytic monomer (PubMed:9485415). Interacts with the MbtH-like protein YbdZ. YbdZ binds to the adenylation domain, but does not alter the structure of the domain (PubMed:27597544). Membrane-associated. Transcriptionally regulated by iron and the fur protein. Modular protein that contains an elongation/condensation domain, an adenylation domain which activates the serine residue into an aminoacyl-AMP ester, a peptidyl carrier protein domain which bears a phosphopantetheinyl arm to attach the activated amino acid and a thioesterase domain (Probable). The thioesterase domain is both a cyclotrimerizing lactone synthetase and an elongation catalyst for ester-bond formation between covalently tethered DHB-Ser moieties (PubMed:10375542). The carrier-thioesterase di-domain forms a compact structure with a well-defined domain interface; the two active sites are at a suitable distance for substrate transfer from the peptidyl carrier protein domain to the thioesterase domain (PubMed:18704088). Phosphopantetheinylation leads to enhanced interaction between the two domains (PubMed:22118682). 4'-phosphopantetheine is transferred from CoA to a specific serine of apo-EntF by EntD (PubMed:9485415). Holo-EntF so formed is then acylated with seryl-AMP (PubMed:9485415). Belongs to the ATP-dependent AMP-binding enzyme family. EntF subfamily. Extended N-terminus.