Regensburg 2007 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 2: Protein Function
BP 2.4: Vortrag
Montag, 26. März 2007, 13:00–13:15, H43
Molecular Dynamics and Secondary Structure Behaviour of the C-Terminus of Vinculin that includes a Membrane Binding Anchor — Gerold Diez1, •James Smith1, Martin Stiebritz2, and Wolfgang Goldmann1 — 1LPMT — 2LS Biotechnik,FAU Erlangen
Vinculin (1066 residues) is a focal adhesion (FA) protein and has three lipid-binding sites, residues 935-978, 1020-1040 and 1052-1066. The first two regions are amphiphatic alpha-helices identified from sequence prediction and later revealed in crystal structures. The third putative lipid-binding region is unstructured and only experimental data has demonstrated that these C-terminal residues act as an essential anchor for membrane association. Our work investigates the molecular dynamical behaviour of the last twenty-one amino acids (residues 1045-1066), represented as a polypeptide in explicit solvent. Different formal charges for one acidic and five basic residues are altered, representing different pH and salt conditions. Our findings show that the polypeptide undergoes different anti-parallel ß-sheet formation. Two mutually exclusive beta-sheets are formed between residues 1047-1058 and between residues 1057-1064. It is likely that in vivo this bi-stable secondary structure behaviour would be influenced by local changes in ionic conditions. The results suggest a mechanism for favourable lipid-binding activation of the vinculin in presence of local ionic or pH gradients. We will investigate which of these two beta-sheets form favourable hydrogen bonds with the polar heads of phospholipids membrane models.