Microscopic evidence for a minus-end-directed power stroke in the kinesin motor ncd

AUTOR(ES)

Wendt, Thomas G.

FONTE

Oxford University Press

RESUMO

We used cryo-electron microscopy and image reconstruction to investigate the structure and microtubule-binding configurations of dimeric non-claret disjunctional (ncd) motor domains under various nucleotide conditions, and applied molecular docking using ncd’s dimeric X-ray structure to generate a mechanistic model for force transduction. To visualize the α-helical coiled-coil neck better, we engineered an SH3 domain to the N-terminal end of our ncd construct (296–700). Ncd exhibits strikingly different nucleotide-dependent three-dimensional conformations and microtubule-binding patterns from those of conventional kinesin. In the absence of nucleotide, the neck adapts a configuration close to that found in the X-ray structure with stable interactions between the neck and motor core domain. Minus-end-directed movement is based mainly on two key events: (i) the stable neck–core interactions in ncd generate a binding geometry between motor and microtubule which places the motor ahead of its cargo in the minus-end direction; and (ii) after the uptake of ATP, the two heads rearrange their position relative to each other in a way that promotes a swing of the neck in the minus-end direction.

Documentos Relacionados

• KAR3-encoded kinesin is a minus-end-directed motor that functions with centromere binding proteins (CBF3) on an in vitro yeast kinetochore.
• The shapes of the motor domains of two oppositely directed microtubule motors, ncd and kinesin: a neutron scattering study.
• Mitotic HeLa cells contain a CENP-E-associated minus end-directed microtubule motor.
• ncd and kinesin motor domains interact with both alpha- and beta-tubulin.
• Rotation of the stalk/neck and one head in a new crystal structure of the kinesin motor protein, Ncd