Insights into dynein motor domain function from a 3.3-Å crystal structure

Dyneins power the beating of cilia and flagella, transport various intracellular cargos and are necessary for mitosis. All dyneins have a similar to 300-kDa motor domain consisting of a ring of six AA+ domains. AT P hydrolysis in the AA+ ring drives the cyclic relocation of a motile element, the linker domain, to generate the force necessary for movement. How the linker interacts with the ring during the AT P hydrolysis cycle is not known. Here we present a 3.3-angstrom crystal structure of the motor domain of Saccharomyces cerevisiae cytoplasmic dynein, crystallized in the absence of nucleotides. The linker is docked to a conserved site on AA5, which is confirmed by mutagenesis as functionally necessary. Nucleotide soaking experiments show that the main AT P hydrolysis site in dynein (AA1) is in a low-nucleotide affinity conformation and reveal the nucleotide interactions of the other three sites (AA2, AA3 and AA4).