Dynein forms a large multisubunit complex, the core of which consists of a ring of AAA ATPase domains. Conformational changes driven by ATP hydrolysis within the ring underlie dynein force generation and motion. Recent structural and biochemical studies have identified the major conformational states of monomeric dynein constructs. However, studies of active dynein dimers are lacking. As a result, the molecular basis by which ATP driven structural changes lead to unidirectional motion of a dimer as a whole is unknown. In our preliminary work, we have used S. cerevisiae to express recombinant dynein motors and characterized dynein stepping behavior in vitro. We are now aiming to dissect the coordination between the nucleotide and conformational states of the motor domains in native and engineered dynein constructs.
Cytoplasmic dynein’s predicted structure. Each motor head (blue) of a dynein dimer is composed of roughly 3000 amino acids. It contains six AAA+ ATPase domains forming a hexagonal ring, 15 nm in diameter. Dynein motor head binds to microtubules through ~10 nm long stalk domain (purple) with a small MT binding domain at the tip (violet). The motor heads are held together by a linker region which is presumably composed of multiple short stretches of a coiled-coil. The linker has been proposed as a mechanical element that coordinates the two rings to power dynein’s motion. At the tail, large number of light chains interacts with dynein for regulatory purposes and cargo recognition.