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Kinetic Insights into the Elongation Reaction of Actin Filaments as a Function of Temperature, Pressure, and Macromolecular Crowding
Author(s) -
Gao Mimi,
Winter Roland
Publication year - 2015
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201500633
Subject(s) - actin , elongation , polymerization , biophysics , actin remodeling , gelsolin , macromolecular crowding , monomer , chemistry , kinetics , macromolecule , mdia1 , filamin , protein filament , microfilament , polymer , materials science , actin cytoskeleton , cytoskeleton , biochemistry , biology , cell , organic chemistry , physics , quantum mechanics , metallurgy , ultimate tensile strength
Actin polymerization is an essential process in eukaryotic cells that provides a driving force for motility and mechanical resistance for cell shape. By using preformed gelsolin–actin nuclei and applying stopped‐flow methodology, we quantitatively studied the elongation kinetics of actin filaments as a function of temperature and pressure in the presence of synthetic and protein crowding agents. We show that the association of actin monomers to the pointed end of double‐stranded helical actin filaments (F‐actin) proceeds via a transition state that requires an activation energy of 56 kJ mol −1 for conformational and hydration rearrangements, but exhibits a negligible activation volume, pointing to a compact transition state that is devoid of packing defects. Macromolecular crowding causes acceleration of the F‐actin elongation rate and counteracts the deteriorating effect of pressure. The results shed new light on the combined effect of these parameters on the polymerization process of actin, and help us understand the temperature and pressure sensitivity of actin polymerization under extreme conditions.