Mammalian Kinesin-3 Motors Are Dimeric In Vivo And Move By Processive Motility Upon Release Of Autoinhibition

Molecular motors transport a wide variety of cellular cargoes that are important for diverse cellular phenomena such as mitosis, polarity, motility,
and secretion. Motor activity must be tightly regulated to ensure that ATP hydrolysis and processive motility occur only upon coupling to the correct
cargo.


In neuronal cells, Kinesin-3 motors drive the transport of presynaptic vesicles and other membrane-bound organelles along microtubule tracks.
Yet the mechanisms of Kinesin-3 motor activation and motility remain controversial. In this study, Kristen Verhey and colleagues, from the University
of Michigan, examine the regulation and motile properties of the Kinesin-3 motor KIF1A. They show that in the absence of cargo, KIF1A motors exist in
a dimeric inactive state that is maintained by two distinct autoinhibitory mechanisms. This suggests a simple model for activation of dimeric motors
upon cargo binding.


They also show that dimeric motors can undergo two mechanisms of motility along microtubule tracks: one-dimensional diffusion and
ATP-driven processive motility. This unique property may facilitate the ability of KIF1A to drive long-distance vesicular transport in neuronal cells.



Citation:

"Mammalian Kinesin-3 motors are dimeric in vivo and move by processive motility upon release of autoinhibition."
Hammond JW, Cai D, Blasius TL, Li Z, Jiang Y, et al. (2009)

PLoS Biol 7(3): e1000072. doi:10.1371/journal.pbio.1000072



Source
Public Library of Science