Observação direta mostra a superposição e grande escala de flexibilidade nos motores de dineína citoplasmática movendo-se pelos microtúbulos

terça-feira, setembro 15, 2015

Direct observation shows superposition and large scale flexibility within cytoplasmic dynein motors moving along microtubules

Hiroshi Imai, Tomohiro Shima, Kazuo Sutoh, Matthew L. Walker, Peter J. Knight, Takahide Kon & Stan A. Burgess

Affiliations Contributions Corresponding author

Nature Communications 6, Article number: 8179 doi:10.1038/ncomms9179

Received 23 April 2015 Accepted 25 July 2015 Published 14 September 2015


Cytoplasmic dynein is a dimeric AAA+ motor protein that performs critical roles in eukaryotic cells by moving along microtubules using ATP. Here using cryo-electron microscopy we directly observe the structure of Dictyostelium discoideum dynein dimers on microtubules at near-physiological ATP concentrations. They display remarkable flexibility at a hinge close to the microtubule binding domain (the stalkhead) producing a wide range of head positions. About half the molecules have the two heads separated from one another, with both leading and trailing motors attached to the microtubule. The other half have the two heads and stalks closely superposed in a front-to-back arrangement of the AAA+ rings, suggesting specific contact between the heads. All stalks point towards the microtubule minus end. Mean stalk angles depend on the separation between their stalkheads, which allows estimation of inter-head tension. These findings provide a structural framework for understanding dynein’s directionality and unusual stepping behaviour.