Force–velocity relationship for multiple kinesin motors pulling a magnetic bead

• Published in: European biophysics journal 2011-09, Vol.40 (9), p.1071-1079
• Main Authors: Fallesen, Todd L., Macosko, Jed C., Holzwarth, G.
• Format: Article
• Language: English
• Subjects: Animals; Bioassays; Biochemistry; Biological and Medical Physics; Biomechanical Phenomena; Biomedical and Life Sciences; Biophysics; Biotin - metabolism; Cattle; Cell Biology; Drosophila Proteins - metabolism; Eukaryotes; Kinesin - metabolism; Kinetics; Life Sciences; Load distribution; Magnetic Fields; Mechanical Phenomena; Membrane Biology; Microspheres; Microtubules - metabolism; Nanotechnology; Neurobiology; Original Paper; Proteins; Streptavidin - metabolism; Velocity; Velocity distribution
• ISSN: 0175-7571; 1432-1017
• DOI: 10.1007/s00249-011-0724-1

Although the velocity of single kinesin motors against an opposing force F of 0–10 pN is well known, the behavior of multiple kinesin motors working to overcome a larger load is still poorly understood. We have carried out gliding assays in which 3–7 Drosophila kinesin-1 motors moved a microtubule at 200–700 μm/s against a 0–31 pN load at saturating [ATP]. The load F was generated by applying a spatially uniform magnetic field gradient to a superparamagnetic bead attached to the (+) end of the microtubule. When F was scaled by the average number of motors 〈 n 〉, the force–velocity relationship for multiple motors was similar to the force–velocity relationship for a single motor, supporting a minimal load-sharing model. The velocity distribution at low load has a single mode consistent with rapid fluctuations of n . However, against a load of 2.5–4.7 pN/motor, additional modes appeared at lower velocity. These observations support the Klumpp–Lipowsky model of multimotor transport [Proc Natl Acad Sci USA 102. 17284–17289 (2005)].