Conformational flexibility of EptA driven by an interdomain helix provides insights for enzyme-substrate recognition.

Many pathogenic gram-negative bacteria have developed mechanisms to increase resistance to cationic antimicrobial peptides by modifying the lipid A moiety. One modification is the addition of phospho-ethano-lamine to lipid A by the enzyme phospho-ethano-lamine transferase (EptA). Previously we reported the structure of EptA from , revealing a two-domain architecture consisting of a periplasmic facing soluble domain and a transmembrane domain, linked together by a bridging helix.