The Mechanical Properties of Talin Rod Domain

Abstract

Focal adhesion protein talin has emerged as a key protein the mechanotransduction pathway linking integrin based cell adhesion to actin cytoskeleton. The force-dependent structural transitions of the c-terminal rod domain, consisting of 13 alpha-helical bundles, are critical for talin's mechanosensing function during cell adhesion and spreading but remain poorly understood. We systematically determined the force-dependent unfolding/refolding kinetics of all talin rod domains and obtained the dynamics of force fluctuation of talin rod under experimentally measured extension fluctuation time trajectories. The results revealed talin rod's role as a viscoelastic spring and tension buffer that maintains at a level < 10 pN along talin mediated force-transmission pathway. These results provide the first quantitative understanding of how talin serves as a mechanical clutch during cell spreading.