ACTIN: structure and function [Elektronische Ressource] : towards an understanding of the conformational states of actin monomer and filament / presented by Thomas Splettstößer

Dissertation submitted to the Combined Faculties for the Natural Sciences and for Mathematics of the Ruperto-Carola University of Heidelberg, Germany for the degree of Doctor of Natural Sciences presented by Diplom-Biologe Thomas Splettstößer born in: Pasewalk oral examination: 15.12.2010 ACTIN: Structure and Function Towards an understanding of the conformational states of actin monomer and filament Referees: Prof. Dr. Jeremy C. Smith Prof. Dr. Robert Russell Abstract Actin is a major structural protein of the eukaryotic cytoskeleton and plays a crucial role in cell motility, adhesion, morphology and intracellular transport. Its biologically active form is the filament (F-actin), which is assembled from monomeric G-actin. In this thesis, the structural characteristics of both G- and F-actin are studied using molecular dynamics simulations. First, the crystallographically-determined 'open' and 'closed' conformational states of G-actin are characterized in aqueous solution, with either ATP or ADP bound in the nucleotide binding pocket. In both nucleotide states, the open state closes in the absence of the actin-binding protein profilin, suggesting that the open state is not a stable conformation of isolated G-actin.