Structural characterization of AS1-membrane interactions from a subset of HAMP domains

► AS1-containing peptides from NarXEc and TarEc become structured in the presence of membrane mimetics. ► AS1 from TarEc forms an amphipathic α-helix upon association with acidic bicelles. ► Residues comprising the control cable of TarEc remain unstructured. ► A conserved prolyl residue separates the unstructured and helical regions. ► The propensity for AS1-membrane interactions correlates with signaling mechanisms and subcellular localization.