G protein-bound conformation of mastoparan-X: heteronuclear multidimensional transferred nuclear overhauser effect analysis of peptide uniformly enriched with 13C and 15N

Biochemistry. 1998 Apr 7;37(14):4782-90. doi: 10.1021/bi972756p.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Carbon Isotopes
  • GTP-Binding Proteins / metabolism*
  • Intercellular Signaling Peptides and Proteins
  • Magnetic Resonance Spectroscopy
  • Nitrogen Isotopes
  • Peptides / chemistry*
  • Peptides / metabolism
  • Protein Conformation
  • Static Electricity


  • Carbon Isotopes
  • Intercellular Signaling Peptides and Proteins
  • Nitrogen Isotopes
  • Peptides
  • mastoparan X
  • GTP-Binding Proteins

Associated data

  • PDB/1A13