The Power Stroke Distance of Human Cytoplasmic Dynein

Abstract

Cytoplasmic dynein-1 is a 1.4 MDa motor protein, which performs essential cargo transport to the minus end of microtubules. Long distance movement of single dynein-1 molecules is induced by binding to its 23-subunit cofactor dynactin and a cargo-adaptor protein. Here we present the cryo-EM structure of isolated human dynein-1 in its inhibited, phi-particle conformation. We achieved a resolution of 3.8Å for the motor domains and 8.4Å in the highly-flexible tail region. We reveal the architecture of the complete complex; identify all subunits, build helices in the tail and a full atomic model for the human dynein-1 motor domains. Mutagenesis to disrupt the interface between the two motor domains is not sufficient to activate dynein-1. Instead dynactin is required to orient the motors in a parallel fashion so that they can interact correctly with microtubules, thus explaining the structural mechanism of dynein-1 activation.