Conformations of kinesin: solution vs. crystal structures and interactions with microtubules

Abstract

Recently, the molecular structures of monomeric and dimeric kinesin constructs in complex with ADP have been determined by X-ray crystallography (Kull et al. 1996; Kozielski et al. 1997 a; Sack et al. 1997). The "motor" or "head" domains have almost identical conformations in the known crystal structures, yet the kinesin dimer is asymmetric: the orientation of the two heads relative to the coiled-coil formed by their neck regions is different. We used small angle solution scattering of kinesin constructs and microtubules decorated with kinesin in order to find out whether these crystal structures are of relevance for kinesin's structure under natural conditions and for its interaction with microtubules. Our preliminary results indicate that the crystal structures of monomeric and dimeric kinesin are similar to their structures in solution, though in solution the center-of-mass distance between the motor domains of the dimer could be slightly greater. The crystal structure of dimeric kinesin can be interpreted as representing two equivalent conformations. Transitions between these or very similar conformational states may occur in solution. Binding of kinesin to microtubules has conformational effects on both, the kinesin and the microtubule. Solution scattering of kinesin decorated microtubules reveals a peak in intensity that is characteristic for the B-surface lattice and that can be used to monitor the axial repeat of the microtubules under various conditions. In decoration experiments, dimeric kinesin dissociates, at least partly, leading to a stoichiometry of 1:1 (one kinesin head per tubulin dimer; Thormählen et al. 1998a) in contrast to the stoichiometry of 2:1 reported for dimeric ncd. This discrepancy is possibly due to the effect of steric hindrance between kinesin dimers on adjacent binding sites.

Temporal and tissue specific gene expression patterns of the zebrafish kinesin-1 heavy chain family, kif5s, during development

“…The motor domain is responsible for ATP-hydrolysis and microtubule binding allowing the complex to move along microtubules. The neck is composed of two regions, a flexible neck linker (NL) thought to be involved in velocity(Kalchishkova and Bohm, 2008) and regulation of directionality, and a coiled coil (NCC) domain thought to be important for Kif5 dimerization(Grummt et al, 1998; Marx et al, 1998). The rigid stalk is composed of two coiled coil regions (CC1/2) which allow for dimerization and two flexible hinge regions (H1/2).…”

Changes in Microtubule Protofilament Number Induced by Taxol Binding to an Easily Accessible Site

“…MAPs permit taxoid binding to and dissociation from microtubules (see "Results"), yet microtubules assembled with MAPs and Taxol have an unmodified protofilament number (27). Similarly, the change in axial spacing between tubulin monomers in microtubules assembled with Taxol (39) has not been observed when microtubules are decorated with kinesin (57). Nevertheless, in studies with microtubule motor proteins (see Introduction) the possibility of transient opening of Taxol microtubules should be considered.…”

The mechanical properties of kinesin-1: a holistic approach

“…This domain induces KHC dimerization [31,32] and has an amino-acid sequence that is highly conserved among kinesin-1 species [33]. Artificial substitution of the sequence does not affect maximal motile velocity or force generation, although coiled coil formation is important [31], suggesting this sequence conservation might be for regulation purposes rather than motility [34].…”