Interaction of the Saccharomyces cerevisiae α-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 α-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 α-factor is highly flexible with only one long-lived identifiable structural feature, a type II β-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 β-turn. In contrast to these results in both solution and lipid environment, Wakamatsu et al. proposed a lipid environment conformation, on the basis of one-dimensional transferred NOE studies in D2O, which does not include the β-turn