Motor driven microtubule shape fluctuations: force from within the lattice.

Area of Science:

• Biophysics
• Cell Biology
• Structural Biology

Background:

• Microtubules (MTs) are crucial cytoskeletal components.
• Molecular motors interact with MTs, influencing their structure and function.
• Internal forces within the MT lattice can cause significant deformations.

Purpose of the Study:

• To develop a general theory for microtubule deformations induced by molecular motors.
• To explain observed MT deformation shapes (S and V) and the role of tubulin vacancies.
• To quantify the forces exerted by motors like katanin on the MT lattice.

Main Methods:

• Theoretical modeling of internal force doublets within the MT lattice.
• Comparison of theoretical predictions with experimental observations from literature.
• Analysis of the influence of tubulin vacancies and lattice defects on MT deformation.

Main Results:

• Two basic internal excitations (S and V shapes) were described and matched with experimental data.
• Tubulin vacancies and defects were shown to amplify MT deformations.
• The ratio of MT stretch and shear moduli was determined to be approximately 6 x 10^5.
• Forces induced by katanin were estimated in the tens of piconewtons (pN).

Conclusions:

• Molecular motors can animate microtubules internally, inducing slack without external cross-linking.
• This internal motor-driven mechanism is analogous to motor function in axonemes.
• The study provides quantitative insights into motor-MT interactions and MT mechanical properties.