Zervamicins, a structurally characterised peptide model for membrane ion channels.
Agarwalla S., Mellor IR., Sansom MS., Karle IL., Flippen-Anderson JL., Uma K., Krishna K., Sukumar M., Balaram P.
Voltage dependent membrane channels are formed by the zervamicins, a group of alpha-aminoisobutyric acid containing peptides. The role of polar residues like Thr, Gln and Hyp in promoting helical bundle formation is established by dramatically reduced channel lifetimes for a synthetic apolar analog. Crystal structures of Leu1-zervamicin reveal association of bent helices. Polar contacts between convex faces result in an 'hour glass' like arrangement of an aqueous channel with a central constriction. The structure suggests that gating mechanisms may involve movement of the Gln11 carboxamide group. Gln3 may play a role in modulating the size of the channel mouth.