Paper Citing NAMD - Abstract
Puklin-Faucher, Eileen; Vogel, Viola
Integrin Activation Dynamics between the RGD-binding Site and the Headpiece Hinge
JOURNAL OF BIOLOGICAL CHEMISTRY, 284:36557-36568, DEC 25 2009
Integrins form mechanical links between the extracellular matrix and the cytoskeleton. Although integrin activation is known to be regulated by an allosteric conformational change, which can be induced from the extracellular or intracellular end of the molecule, little is known regarding the sequence of structural events by which signals propagate between distant sites. Here, we reveal with molecular dynamics simulations of the FnIII(10)-bound alpha(V)beta(3) integrin headpiece how the binding pocket and interdomain beta A/hybrid domain hinge on the distal end of the beta A domain are allosterically linked via a hydrophobic T-junction between the middle of the alpha 1 helix and top of the alpha 7 helix. The key results of this study are: 1) that this T-junction is induced by ligand binding and hinge opening, and thus displays bidirectionality; 2) that formation of this junction can be accelerated by ligand-mediated force; and 3) how formation of this junction is inhibited by Ca(2+) in place of Mg(2+) at the site adjacent to the metal ion-dependent adhesion site ("ADMIDAS"). Together with recent experimental evidence that integrin complexes can form catch bonds (i.e. become strengthened under force), as well as earlier evidence that Ca(2+) at the ADMIDAS results in lower binding affinity, these simulations provide a common structural model for the dynamic process by which integrins become activated.
