Kinesin–microtubule binding depends on both nucleotide state and loading direction

AUTOR(ES)

Uemura, Sotaro

FONTE

The National Academy of Sciences

RESUMO

Kinesin is a motor protein that transports organelles along a microtubule toward its plus end by using the energy of ATP hydrolysis. To clarify the nucleotide-dependent binding mode, we measured the unbinding force for one-headed kinesin heterodimers in addition to conventional two-headed kinesin homodimers under several nucleotide states. We found that both a weak and a strong binding state exist in each head of kinesin corresponding to a small and a large unbinding force, respectively; that is, weak for the ADP state and strong for the nucleotide-free and adenosine 5′-[β,γ-imido]triphosphate states. Model analysis showed that (i) the two binding modes in each head could be explained by a difference in the binding energy and (ii) the directional instability of binding, i.e., dependence of unbinding force on loading direction, could be explained by a difference in the characteristic distance for the kinesin–microtubule interaction during plus- and minus-end-directed loading. Both these factors must play an important role in the molecular mechanism of kinesin motility.

Documentos Relacionados

• Kinesin swivels to permit microtubule movement in any direction.
• Directional loading of the kinesin motor molecule as it buckles a microtubule.
• Dynein and kinesin share an overlapping microtubule-binding site
• Characterization of microtubule binding domains in the Arabidopsis kinesin-like calmodulin binding protein.
• Direction of microtubule movement is an intrinsic property of the motor domains of kinesin heavy chain and Drosophila ncd protein.