Titin domains progressively unfolded by force are homogenously distributed along the molecule.

ABSTRACT: Titin is a giant filamentous protein of the muscle sarcomere in which stretch induces the unfolding of its globular domains. However, the mechanisms of how domains are progressively selected for unfolding and which domains eventually unfold have for long been elusive. Based on force-clamp optical tweezers experiments we report here that, in a paradoxical violation of mechanically driven activation kinetics, neither the global domain unfolding rate, nor the folded-state lifetime distributions of full-length titin are sensitive to force. This paradox is reconciled by a gradient of mechanical stability so that domains are gradually selected for unfolding as the magnitude of the force field increases. Atomic force microscopic screening of extended titin molecules revealed that the unfolded dom

SUBMITTER: Bianco P 

PROVIDER: S-EPMC4621543 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature