Recombinant E.coli entE protein

EntE is a key adenylation domain-containing enzyme involved in the biosynthesis of enterobactin, a high-affinity iron-chelating siderophore produced by *Escherichia coli* and other Gram-negative bacteria. Under iron-limiting conditions, bacteria synthesize enterobactin to scavenge extracellular ferric iron (Fe³⁺), which is essential for survival and virulence. The entE gene is part of the *ent* operon (entABCDEF), encoding nonribosomal peptide synthetase (NRPS)-like machinery. EntE specifically catalyzes the ATP-dependent activation of 2.3-dihydroxybenzoate (DHB), a precursor derived from chorismate, forming an adenylated intermediate (DHB-AMP). This activated substrate is then transferred to the phosphopantetheine arm of the carrier protein EntB, facilitating subsequent condensation steps to assemble the cyclic trilactone scaffold of enterobactin.

Recombinant EntE protein is engineered for overexpression in heterologous systems (e.g., *E. coli*) to study its structure, enzymatic mechanism, and interactions with other enterobactin synthesis components. Structural analyses (e.g., X-ray crystallography) reveal conserved motifs critical for adenylation activity, including the ATP-binding P-loop and substrate-binding pockets. EntE’s role in iron acquisition makes it a potential target for antimicrobial strategies, as disrupting siderophore biosynthesis could impair bacterial iron uptake. Studies on recombinant EntE also aid in exploring substrate promiscuity for synthetic biology applications, such as engineering novel siderophores or modifying NRPS pathways. Its biochemical characterization provides insights into the evolutionary adaptation of microbial iron acquisition systems under host-imposed nutritional immunity.