The seminar will take place, the 12th of May at 16h, at the ENSCBP amphitheater, Building B, allée Geoffroy Saint-Hilaire, Pessac.
School of Chemistry, University of Melbourne, Autralia
Antimicrobial peptides (AMP) present an alternative to conventional antibiotics but details of their mechanism of action and the basis for differences in potency observed between different bacterial strains remain unclear. Structural information is crucial for defining the molecular mechanism by which these peptides recognize and interact with a particular lipid membrane.
We present NMR structural investigations of the AMP maculatin 1.1 in different lipid systems. Although the AMP is α-helical, the degree of helicity depended on membrane curvature and surface charge with a greater helical stretch in bicelles compared to micelles. The central core of maculatin was mainly transmembrane in bicelles while the N-terminus was exposed in micelles. MD simulations also showed N-terminal exposure to the solvent and indicated that maculatin bent to adapt to the micelle curvature. Maculatin induced greater headgroup and acyl-chain perturbations for anionic phospholipids in anisotropic bicelles; and appeared to lie on the surface of charged lipid membranes but insert in a transmembrane fashion with neutral membranes. Overall, lipid composition plays a critical role in modulating AMP structure and function.
Professor Frances Separovic is a Biophysical Chemist and Head of the School of Chemistry, University of Melbourne. Frances completed a BA at Macquarie University and a PhD at University of New South Wales while working at CSIRO, Sydney. Following a post-doctoral fellowship at National Institutes of Health (USA), Frances joined the University of Melbourne in 1996. Frances has developed solid-state NMR techniques to determine the structure and dynamics of membrane components in situ, specializing in peptide antibiotics and toxins within phospholipid membranes. Her lab, which specializes in membrane biophysics and biological solid-state NMR, is based at the Bio21 Institute, University of Melbourne.
Frances has served as Assistant Dean (EO) (2001-02) and Associate Dean (2009-10) of the Science Faculty and General Treasurer of the Royal Australian Chemical Institute (2008-10). She was elected to Council of the Biophysical Society (USA) for 2007-10; Treasurer of Lorne Protein Conference (2006-09), Council of International Union of Pure & Applied Biophysics, IUPAB (2002-05); President of Australian Society for Biophysics, ASB (1999-2001, 2012-14); President of Australian New Zealand Society for Magnetic Resonance, ANZMAG (2011-13); and an editorial board member of Accounts of Chemical Research and editor of Biochimica Biophysica Acta – Biomembranes and European Biophysics Journal. Frances has organized 40 major scientific conferences and published over 180 papers in international journals. She was awarded the ASB Robertson Medal in 2009, the ANZMAG Medal in 2011 and was elected Fellow of the Biophysical Society (USA), ISMAR Fellow, and Fellow of the Australian Academy of Science in 2012. http://www.chemistry.unimelb.edu.au/professor-frances-separovic