The collective role of bending, stretching, and polydispersity in microtubule mechanics and hydrodynamics

Microtubules (MTs) organize into various structures by modulating their physico-chemical and electro-mechanical properties. Their size and flexibility are crucial for maintaining the cell's mechanical strength and its ability to respond to external forces. Translational and rotational diffusion enhance MTs' capacity to locate and bind to targets. In addition, cells regulate asymmetric MT length growth and polydispersity to maintain proper cytoskeletal organization in response to functional demands. Therefore, understanding these properties accurately is essential for grasping their critical roles in cellular functions. In this study, we develop a comprehensive framework to characterize the collective effects of hydrodynamic interactions, polydispersity, bending, and stretching on the hydrodynamic and mechanical properties of MT solutions. The approach integrates dynamic light scattering (DLS), a reliable sample preparation protocol, and an optimized scattering theory for polydisperse semiflexible polymers, yielding accurate, reproducible results from autocorrelation functions measured under conditions that simulate the physiological environment. Overall, the approach offers an alternative to conventional post-analysis DLS tools for analyzing experimental autocorrelation data in filamentous systems with variable stiffness and length and under various intracellular conditions, thereby providing a close relationship among the biophysical parameters describing filaments, their surrounding environment, and their influence on the complex and dynamic behavior of these systems.