1a13

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G PROTEIN-BOUND CONFORMATION OF MASTOPARAN-X, NMR, 14 STRUCTURES

Overview

Mastoparans, a family of tetradecapeptides from wasp venom, have been used, as convenient low molecular weight models of receptors coupled to, GTP-binding regulatory proteins (G proteins) for the understanding of the, interaction between G proteins and receptors. Sukumar and Higashijima have, analyzed the conformation of mastoparan-X (MP-X) bound to the G protein, alpha-subunit using proton two-dimensional transferred nuclear Overhauser, effect (TRNOE) spectroscopy [Sukumar, M., and Higashijima, T. (1992) J., Biol. Chem., 267, 21421-21424]. The resultant structure, however, was not, well-defined due to severe overlap of peptide proton resonances. To, determine the G protein-bound conformation of MP-X in detail, we have, analyzed this interaction by heteronuclear multidimensional TRNOE, experiments of MP-X uniformly enriched with 15N and/or 13C. By solving the, overlap problem, we were able to determine the precise conformation of, MP-X bound to Gi1alpha: the peptide adopts an amphiphilic alpha-helix from, Trp3 to C-terminal Leu14, and the atomic root-mean-square deviation (rmsd), values in this portion about the averaged coordinates were 0.27 +/- 0.07 A, for the backbone atoms (N, Calpha, C') and 0.84 +/- 0.16 A for all heavy, atoms. These values are much smaller than the corresponding rmsd values of, the structures obtained from the proton 2D TRNOE spectrum alone: 1.70 +/-, 0.41 A for the backbone atoms (N, Calpha, C') and 2.84 +/- 0.51 A for all, heavy atoms. Our results indicate that the heteronuclear multidimensional, TRNOE experiments of peptides uniformly enriched with stable isotopes are, a very powerful tool for analyzing the conformation of short peptides, bound to large proteins. We will also discuss the structure-activity, relationships of mastoparans in activating G proteins on the basis of the, precise structure of MP-X bound to Gi1alpha.

About this Structure

1A13 is a Single protein structure of sequence from Vespa simillima xanthoptera with NH2 as ligand. Full crystallographic information is available from OCA.

Reference

G protein-bound conformation of mastoparan-X: heteronuclear multidimensional transferred nuclear overhauser effect analysis of peptide uniformly enriched with 13C and 15N., Kusunoki H, Wakamatsu K, Sato K, Miyazawa T, Kohno T, Biochemistry. 1998 Apr 7;37(14):4782-90. PMID:9537994

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