Friday, March 9, 2007

241 Hunt Hall

From 2:00 p.m. to 3:00 p.m.

Membranes and Proteins: Spectrocopy and Modeling

Claus Hélix Nielsen, Ph.D.

Associate Professor, Quantum Protein Center

Department of Physics, Building 309, Office 102

Technical University of Denmark

2800 Lyngby, Denmark

Tel: +45 4525 3330

e-mail: Claus.Nielsen@fysik.dtu.dk

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In this talk I will present some of our ongoing work related to lipid-protein interactions. The continuum elastic model for the energetic of inclusion-induced bilayer deformation describes well how changes in bilayer material properties can influence ion channel function. For membrane spanning carriers, the interplay between ion translocation and conformational change is complex as the conformational change is coupled to the catalytic event. This complicates the use of energetic membrane models in understanding membrane-protein interactions. We have therefore investigated if Raman spectroscopy could provide in situ information about conformational changes in membrane spanning proteins. In particular we have investigated two P-type ATPases, the NaK and SERCA ATPases with the aim to understand why the two closely related proteins require different membrane composition in order to work optimally. P-type ATPases and many other membrane spanning proteins are enriched in interfacial aromatic residues. Their exact role has been related to an anchoring effect, but the exact mechanisms remain unclear. We have studied this in model systems using MD simulations and I will discuss our plans to address this issue experimentally using Raman spectroscopy. Finally some results from fluorescence microscopy studies on membrane domain formation and induced vesicle fission in living cells will be presented and discussed in the context of bilayer elasticity.