The Effect of Inter-Protofilament Sliding on the Mechanics of Microtubules

Inter-Protofilament (PF) sliding has been observed experimentally for microtubules (MTs) in eukaryotic cells. This paper aims to quantitatively examine its effect on the static bending and transverse vibration of MTs. In calculating the bending stiffness and the frequencies a newly developed molecular structural mechanics (MSM) technique able to capture the relative sliding between the adjacent PFs was compared with the Euler beam model where the inter-PF sliding is neglected. The difference between the two models thus measures the effect of the inter-PF sliding on the mechanics of MTs. Significant effect of the inter-PF sliding is achieved in the present study, leading to lower bending stiffness and the downshift of the frequency of MT vibration. In particular, the effect of the inter-PF sliding is found to increase with decreasing deformation wavelength-to-diameter ratio.