PhD Defence Asger Tønnesen


Title: Geometrical membrane curvature (MC) changes transmembrane protein structure and function

Abstract:
Transmembrane (TM) proteins are embedded in cellular membranes of varied lipid composition and shape. The membrane shape is described by a geometrical membrane curvature (MC). Lipid composition is known to affect directly TM protein structure and function.

Our data show that MC plays an equally important regulatory role on TM protein structure and function. To study the role of MC on TM proteins, we devised a fluorescence based platform of surface immobilized vesicles of different sizes that each carries a single TM protein.

We found a dramatic allosteric MC regulation (10,000-fold inhibito- ion) of the proteotypic transmembrane β-barrel pore α-hemolysin by physiologically abundant MC ranging from 1/25–1/250 nm-1.

This pore inhibition revealed a MC imposed pore deformation that equaled a deformation energy ~ 7 kBT. This energy would most likely modulate the structure and function of TM proteins in general

There will be a reception in D203 after the defense ~17 pm.

PhD Panel:
Supervisor: Dimitrios Stamou, Group Leader “Bionanotechnology and Nanomedicine Laboratory, Department of Chemistry and The Nano Science Center, Copenhagen University (stamou@nano.ku.dk)
Prof. Patricia Bassereua, Group Leader “ Membrane and Cellular Functions” PhysicoChimie Curie, Institut Curie
Prof. Luis Bagatolli, Head of Research “Membrane Biophysics and Biophotonics group”, Department ofBiochemistry and Molecular Biology, Syddansk Universitet