J. Phys. IV France 03 (1993) C8-241-C8-244
Effect of organic cryosolvents on actin structures and actin/[MATH]-actinin binding geometriesE. PAJOT-AUGY1, 2 and M.A.V. AXELOS3
1 Unité de Recherche en Développement Concerté, INRA-INSERM (U. 310), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
2 INRA, Laboratoire de Biologie Cellulaire et Moléculaire, Unité d'Ingénierie des Protéines, Domaine de Vilvert, 78352 Jouy en Josas cedex, France
3 INRA, Laboratoire de Physicochimie des Macromolécules, BP. 527, 44026 Nantes cedex 03, France
Cryopreservation procedures of living cells involve the use of organic solvents against freezing damage. An efficient cryoprotection might be achieved by obtaining a cytoplasmic gel able to reduce water flux and avoid crystallization. Small angle X-ray scattering experiments were performed at LURE (Orsay, France) to investigate the effects of 1,2- propanediol and glycerol on the structure of actin, a major cytoplasmic protein, and on the binding geometries of actin to [MATH]-actinin, an interconnecting protein. In the presence of 1,2-propanediol, monomeric G-actin exhibits oligomerization into short rod-like structures very close to that of salt-polymerized actin filaments (F-actin). In the presence of [MATH]-actinin. F-actin filaments aggregate into thick and tight bundles. The scattering pattern in the presence of propanediol suggests a "ladder-like" structure with a tilt angle of the [MATH]-actinin molecule relative to F-actin filaments. This angle is even larger with glycerol. The resulting loose structures favor the formation of a microporous network. All these results support previous electron microscopy observations and the structural mechanisms deduced from rheological measurements.
© EDP Sciences 1993