X-ray structure of a functional full-length dynein motor domain.

Dyneins are large microtubule-based motors that power a wide variety of cellular processes. Here we report a 4.5-Å X-ray crystallographic analysis of the entire functional motor domain of cytoplasmic dynein with ADP from Dictyostelium discoideum, which has revealed the detailed architecture of the functional units required for motor activity, including the ATP-hydrolyzing ring, the long coiled-coil microtubule-binding stalk and the force-generating rod-like linker. We discovered a Y-shaped protrusion composed of two long coiled coils-the stalk and the newly identified 'strut'. This structure supports our model in which the strut coiled coil actively contributes to communication between the primary ATPase site in the ring and the microtubule-binding site at the tip of the stalk coiled coil. Our work also provides insight into how the two motor domains are arranged and how they interact with each other in a functional dimer form of cytoplasmic dynein.