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BP: Fachverband Biologische Physik

BP 25: Membranes

BP 25.8: Vortrag

Freitag, 27. März 2009, 12:30–12:45, HÜL 186

In vitro characterization of vinculin’s lipid membrane-interacting domain, helix 3 — •Volker Wirth¹, Felix List², Gerold Diez¹, Wolfgang H. Ziegler³, and Wolfgang H. Goldmann¹ — ¹Center for Medical Physics and Technology, Friedrich-Alexander-University of Erlangen-Nuremberg, Germany — ²Institute of Biophysics and Physical Biochemistry, University of Regensburg, Germany — ³IZKF, University of Leipzig, Germany

The focal adhesion protein vinculin plays an important role in cell migration and adhesion. Binding of vinculin to lipid membranes ensures these processes. Helix 3 (residues 944 – 972) is one of three potential membrane interaction sites that has been reported on the tail domain. In pull-down assays using artificial lipid membranes it was demonstrated that, when helix 3 is mutated on position K952, K956, R963, R966 to Q, its interaction with acidic phospholipid vesicles is impaired. To date, no data exist on the nature of the interaction.

Using differential scanning calorimetry on wildtype helix 3 we could show that it inserts into lipid vesicles consisting of dimyristoyl-L-a-phosphatidylcholine (DMPC) and negatively-charged dimyristoyl-L-a-phosphatidylserine (DMPS). However, when mutating the four basic residues on helix 3, the insertion into lipid vesicles was reduced. Examining the secondary structure of wildtype helix 3 in the presence and absence of DMPC/DMPS lipid vesicles by CD-spectroscopy showed a conformational shift. These observations indicate that the electrostatic interaction of the basic residues on helix 3 induce the insertion into the hydrophobic core.