Poster Presentation 2014 International Biophysics Congress

Modelling the interactions of Equinatoxin II with micelles (#613)

Daniel Weber 1 , Shenggen Yao 2 , Nejc Rojko 3 , Gregor Anderluh 3 , Terry Lybrand 4 , Matthew Downton 5 , John Wagner 5 , Frances Separovic 1
  1. School of Chemistry, University of Melbourne, Melbourne, VIC, Australia
  2. Bio21 Institute, University of Melbourne, Melbourne, VIC, Australia
  3. Laboratory for Molecular Biology & Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
  4. Center for Structural Biology, Department of Chemistry, Vanderbilt University, Nashville, TN, USA
  5. IBM Research Collaboratory for Life Sciences, Victorian Life Sciences Computation Initiative, University of Melbourne, Melbourne, VIC, Australia

Equinatoxin II (EqtII) is a 179-residue toxin from the venom of the sea anemone Actinia equina.  EqtII is a member of the actinoporin family of proteins, which have potent lytic activity towards membranes containing sphingomyelin (SM). To gain insight into the atomic-level details governing SM selectivity, a series of all-atom molecular dynamics simulations were performed to model the binding of EqtII to micelles of n-dodecylphosphocholine (DPC) and acetyl-SM (Ac-SM). These models are in good agreement with our concurrent high-resolution solution NMR studies and prior data1  that suggest membrane binding is dependent on a conserved cluster of aromatic amino acids. Furthermore, methods have been developed to calculate the potential of mean force (PMF) over trajectories describing the approach and release of monomeric EqtII from DPC  and Ac-SM micelles, which have provided valuable thermodynamic information regarding the attachment of EqtII to membranes, and possibly a mechanism responsible for SM selectivity.

  1. Anderluh G, Razpotnik A, Podlesek Z, Maček P, Separovic F, Norton RS. Interaction of the eukaryotic pore-forming cytolysin equinatoxin II with model membranes: 19F NMR studies. Journal of Molecular Biology. 2005;347:27-39.
  2. Bakrač B, Gutiérrez-Aguirre I, Podlesek Z, Sonnen AFP, Gilbert RJC, Maček P, Lakey JH, Anderluh G. Molecular determinants of sphingomyelin specificity of a eukaryotic pore-forming toxin. Journal of Biological Chemistry. 2008;283:18665-77