Coordination between Motor Domains in Processive Kinesins
Journal of Biological Chemistry
Among cellular functions that kinesins perform, their ability to walk along the microtubules transporting specific cargoes is the most fascinating (1, 2). The complexity of this phenomenon and tremendous scientific efforts put toward dissecting the mechanisms underlying it have led to conflicting models explaining how kinesins might travel long distances without dissociating from their biological track (e.g. move "processively" (3)). Although these models differ, for conventional kinesin dimer
... onal kinesin dimer the favored one predicts that the two kinesin heads bind alternatively to the track, taking 80-Å steps along the microtubule while hydrolyzing one ATP molecule per step (4 -6). This "hand-over-hand" model (7, 8) also predicts that the two kinesin heads remain enzymatically "out of phase" (e.g. at different stages of the ATP hydrolysis cycle), ensuring that, at any given tug, at least one of the two motor domains remains strongly attached to the track. Many technologically marvelous papers (9 -18) illustrate the importance of coordination between the motor domains of kinesin during its processive movement. We review the phenomenon of kinesin processivity from a complementary perspective by considering specific structural features of the motor domains that underlie their coordination.