Mechanical splitting of microtubules into protofilament bundles by surface-bound kinesin-1

Area of Science:

• Biophysics
• Cellular Biology
• Nanotechnology

Background:

• Microtubule (MT) gliding motility by kinesin-1 motors is crucial for cellular processes and bioanalytical devices.
• Mechanical forces during MT transport can lead to wear and fragmentation.
• Understanding MT mechanical properties is key for optimizing motor-based applications.

Purpose of the Study:

• To investigate the longitudinal splitting of microtubules (MTs) into protofilament bundles (PFBs) by kinesin-1 motors.
• To characterize the properties and motility of these PFBs.
• To identify factors influencing PFB formation.

Main Methods:

• Utilized surface-tethered kinesin-1 motors to drive MT motility.
• Employed fluorescence microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM) to analyze PFBs.
• Varied kinesin motor density, kinesin-surface tether length, and MT modifications (GMPCPP, paclitaxel).

Main Results:

• Demonstrated that kinesin motors can split MTs longitudinally into protofilament bundles (PFBs).
• Showcased that PFBs remain mobile on surfaces and exhibit significantly higher curvature than intact MTs.
• Found that increased kinesin density and shorter tethers promote PFB formation.
• Observed no effect on PFB formation with GMPCPP modification or higher paclitaxel concentrations.

Conclusions:

• Kinesin-mediated mechanical forces can induce longitudinal splitting of MTs into functional PFBs.
• PFBs possess unique mechanical properties, including high curvature and continued motility.
• Optimizing kinesin motor density and tether length can control PFB formation for potential applications in nanodevices.