How rigid is a microtubule?

Microtubules are cytoskeletal filaments responsible for the intracellular organization and cell morphology. Their mechanical properties are regulated through the nucleotide state of the tubulin dimers, the binding of drugs, posttranslational modifications, and microtubule-associated proteins. Interestingly, microtubule-stabilizing factors have differential effects on microtubule mechanics, but whether stabilizers have cumulative effects on mechanics, or one effect dominates another is unclear. 

 

To address these questions, we use the freely fluctuating filaments method in combination with bootstrapping to investigate whether purification, labeling, age, or the presence of MAPs alter stabilized, microtubule mechanics. We determined that the purification process and the microtubules' age cause an effect on their stiffness, but the rhodamine labeling process used to image the microtubules does not. In addition, we also determined the persistence length distribution of a large population of microtubules treated with different stabilizers, including Taxol, GMPCPP, GTP-γ- S, tau, and MAP4. We find that combinations of these stabilizers have novel effects on the mechanical properties of microtubules.