Solution structures of dimeric kinesin and ncd motors

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Motors

Background:

• Kinesin motor proteins are crucial for intracellular transport, utilizing microtubule-based motility.
• Their dimeric structure dictates motility characteristics, but crystal structures lack solution-state information.
• Understanding solution structures is key to elucidating kinesin function.

Purpose of the Study:

• To investigate the solution structures of Drosophila ncd 281-700 (NCD281) and human kinesin 1-420 (hKIN420).
• To compare solution structures with crystallography-based models.
• To identify discrepancies and understand the conformational states of kinesin dimers in solution.

Main Methods:

• Low-angle X-ray and neutron scattering techniques were employed.
• Scattering profiles were collected for NCD281 and hKIN420.
• Data were compared with models derived from crystal structures of NCD281 and rat kinesin 1-379 (rKIN379).

Main Results:

• NCD281 solution structure agrees with its crystallography-based model (Rg = 3.60 nm).
• hKIN420 solution structure shows a significantly smaller radius of gyration (Rg = 4.05 nm) than its model.
• hKIN420 scattering patterns deviate from the crystal structure model, suggesting altered catalytic core orientation and a mushroom-like shape.

Conclusions:

• Kinesin dimer structures in solution differ from crystal structures, particularly for human kinesin.
• The catalytic cores of hKIN420 in solution exhibit different orientations and closer proximity than predicted by crystal structures.
• Solution scattering provides critical insights into the dynamic conformational states of kinesin motor proteins.