Structural Model for Tubulin Recognition and Deformation by Kinesin-13 Microtubule Depolymerases

Abstract

To elucidate the structural basis of the mechanism of microtubule depolymerization by kinesin-13s, we analyzed complexes of tubulin and the Drosophila melanogaster kinesin-13 KLP10A by electron microscopy (EM) and fluorescence polarization microscopy. We report a nanometer-resolution (1.1 nm) cryo-EM three-dimensional structure of the KLP10A head domain (KLP10AHD) bound to curved tubulin. We found that binding of KLP10AHD induces a distinct tubulin configuration with displacement (shear) between tubulin subunits in addition to curvature. In this configuration, the kinesin-binding site differs from that in straight tubulin, providing an explanation for the distinct interaction modes of kinesin-13s with the microtubule lattice or its ends. The KLP10AHD-tubulin interface comprises three areas of interaction, suggesting a crossbow-type tubulin-bending mechanism. These areas include the kinesin-13 family conserved KVD residues, and as predicted from the crossbow model, mutating these residues changes the orientation and mobility of KLP10AHDs interacting with the microtubule.

Prime movers: the mechanochemistry of mitotic kinesins

“…and to highly curved tubulin rings formed by the drug dolastatin [G] 178 . Electron microscopy shows that KIF2 proteins bind between neighbouring tubulin heterodimers 179 in a protofilament, using three contacts (extended L2, L8 and alpha 4-L12; FIG.2)) to bend and stretch the 179 heterodimers 179 . KIF2 dimers probably bridge neighbouring protofilaments 178 .…”

Structural basis for the extended CAP-Gly domains of p150 glued binding to microtubules and the implication for tubulin dynamics

“…This curved morphology of tubulin oligomers can also be observed in GDP-tubulin rings (20), which is actually the preferred nucleotide state for depolymerized tubulin (21). Furthermore, curved protofilaments are observed at the depolymerizing ends of microtubules (17,22,23). Therefore, we asked whether the hydrolysis of GTP occurs coincidently with tubulin oligomerization.…”

Role and regulation of kinesin-8 motors through the cell cycle

“…Role and regulation of kinesin-8 motors 207 Shipley et al 2004;Tan et al 2008;Asenjo et al 2013). Kif18A also contains an extended loop 2 region but this lacks the critical KVD residues, arguing it performs a different function (Peters et al 2010).…”