Membrane-bound conformation of mastoparan-X, a G-protein-activating peptide

Abstract

Mastoparan-X, a tetradecapeptide from wasp venom, has been proposed to cause secretion from various kinds of cells by the direct activation of GTP-binding regulatory proteins (G proteins) that couple to phospholipase C. The mechanism of the activation has been shown to be very similar to that of G-protein-coupled receptors in vitro, and the interaction with membranes seems to be very important for the activation of G proteins that are membrane-bound [Higashijima, T., Uzu, S., Nakajima, T., & Ross, E. M. (1988) J. Biol. Chem. 263, 6491-6494]. We report here the precise vesicle-bound conformation of mastoparan-X in the presence of perdeuterated phospholipid vesicles, determined by two-dimensional 1H-NMR analyses of transferred nuclear Overhauser effects, combined with distance geometry and molecular dynamics calculations. Of 14 amino acid residues, the C-terminal 12 residues take an alpha-helical conformation upon binding to the phospholipid bilayer. The overall structure of the alpha-helix is amphiphilic, with three lysine side chains located on one side and with hydrophobic side chains on the other side. This conformation of mastoparan-X was maintained both in the gel and in the liquid-crystalline phases of the membranes. The conformation described herein will provide a useful basis for understanding conformation-activity relationships of mastoparan analogs as activators of G proteins. These studies will help to design novel potent analogs for the regulation of G proteins and to analyze receptor-G-protein interactions.

A region of the 75 kDa neurotrophin receptor homologous to the death domains of TNFR‐I and Fas

“…To investigate resemblances between modeled receptors and mastoparan, a three-dimensional representation was constructed for the fourteen-residue peptide. The mastoparan model relaxed to a total energy of-45.5 kcal/mol, and closely matched the membrane-bound structure of mastoparan-X obtained by 2D-NMR [28]. Like MP-X, modeled mastoparan (Fig.…”

“…Like MP-X, modeled mastoparan (Fig. 5) forms an amphiphilic helix in which five aliphatic sidechains contribute to a non-polar surface [28]. This surface has several features in common with the non-polar surfaces of the receptor models (Fig.…”

“…Amino acid substitutions in these peptides can produce molecules that neither stimulate G-proteins nor form helices [15,17,28]. To evaluate chemical similarities at critical positions, death-domain sequences containing putative amphiphilic helices were aligned with biologically-active mastoparans and melittin (Fig.…”

Mastoparan Changes the Cellular Localization of Gαq/11and Gβ through Its Binding to Ganglioside in Lipid Rafts

“…When mastoparan is bound to a phospholipid bilayer, the C-terminal 12 residues of mastoparan form ␣-helix structure with three Lys residues' positively charged hydrophilic side chains located on one side and with hydrophobic side chains on the other side (Wakamatsu et al, 1992). Taken in the light of the conformation of mastoparan in lipid bilayers, the electrostatic interaction between Lys residue side of mastoparan and gangliosides on cell surface is suggested as the first step of cell recognition, and then the hydrophobic side enters into the phospholipid bilayer.…”

A Gs-Selective Analog of the Receptor-Mimetic Peptide Mastoparan Binds to Gsα in a Kinked Helical Conformation

“…Vesicles obtained by this procedure are expected to have a diameter of 200-300 Å (Wakamatsu et al, 1992).…”