Solid-state NMR and simulation studies of equinatoxin II N-terminus interaction with lipid bilayers

Lam, YH; Hung, A; Norton, RS; Separovic, F; Watts, A

Author(s): Lam, YH; Hung, A; Norton, RS; Separovic, F; Watts, A;
Details: Publication Year 2010-03,Volume 78,Issue #4,Page 858-872
Journal Title: PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS
Publication Type: Journal Article
Abstract: The interaction with model membranes of a peptide, EqtII(1-32), corresponding to the N-terminal region of the pore-forming toxin equinatoxin II (EqtII) has been studied using solid-state NMR and molecular dynamics (MID) simulations. The distances between specifically labeled nuclei in [(19)F-para]Phe16-[1-(13)C]Leu19 and [(19)F-para]Phe16-[(15)N]Leu23 analogs of EqtII(1-32) measured by REDOR in lyophilized peptide were in agreement with published crystal and solution structures. However, in both DMPC and mixed DMPC:SM membrane environments, significant changes in the distances between the labeled amino acid pairs were observed, suggesting changes in helical content around the experimentally studied region, 16-23, in the presence of bilayers. (19)F-(31)P REDOR experiments indicated that the aromatic ring of Phe16 is in contact with lipid headgroups in both membrane environments. For the DMPC:SM mixed bilayers, a closer interaction between Phe16 side chains and lipid headgroups was observed, but an increase in distances was observed for both labeled amino acid pairs compared with those measured for EqtII(1-32) in pure DMPC bilayers. The observed differences between DMPC and DMPC:SM bilayers may be due to the greater affinity of EqtII for the latter. MD simulations of EqtII(1-32) in water, on a pure DMPC bilayer, and on a mixed DMPC:SM bilayer indicate significant peptide secondary structural differences in the different environments, with the DMPC-bound peptide adopting helical formations at residues 16-24, whereas the DMPC:SM-bound peptide exhibits a longer helical stretch, which may contribute to its enhanced activity against PC:SM compared with pure PC bilayers.
Publisher: WILEY-LISS
Keywords: PORE-FORMING TOXIN; ANEMONE ACTINIA-EQUINA; SEA-ANEMONE; MOLECULAR-DYNAMICS; SECONDARY STRUCTURE; PHASE COEXISTENCE; MODEL MEMBRANES; CYTOLYSIN; SPHINGOMYELIN; PROTEIN
Publisher's Version: https://doi.org/10.1002/prot.22612
Terms of Use/Rights Notice: Refer to copyright notice on published article.

Creation Date: 2010-03-01 12:00:00