Interaction of the Saccharomyces cerevisiae alpha-factor with phospholipid vesicles as revealed by proton and phosphorus NMR.

Proton and phosphorus-31 nuclear magnetic resonance (1H and 31P NMR) studies of the interaction between a tridecapeptide pheromone, the alpha-factor of Saccharomyces cerevisiae, and sonicated lipid vesicles are reported. 31P NMR studies demonstrate that there is interaction of the peptide with the phosphorus headgroups, and quasielastic light scattering (QLS) studies indicate that lipid vesicles increase in size upon addition of peptide. Previous solution (aqueous and DMSO) studies from this laboratory indicate that alpha-factor is highly flexible with only one long-lived identifiable structural feature, a type II beta-turn spanning the central portion of the peptide. Two-dimensional (2D) 1H nuclear Overhauser effect spectroscopy (NOESY) studies demonstrate a marked ordering of the peptide upon interaction with lipid, suggesting a compact N-terminus, in addition to a stabilized beta-turn. In contrast to our results in both solution and lipid environment, Wakamatsu et al. [Wakamatsu, K., Okada, A., Suzuki, M., Higashijima, T., Masui, Y., Sakakibara, S., & Miyazawa, T. (1986) Eur. J. Biochem. 154, 607-615] proposed a lipid environment conformation, on the basis of one-dimensional transferred NOE studies in D2O, which does not include the beta-turn.