Microtubule rigidity and associated stability phenomena

Microtubules (MTs) are polymers of alpha-beta tubulin dimers and are the most rigid part of the cytoskeleton in eukaryotic cells. Extreme cold and heat are known to cause MT depolymerization. Several published reports showed that MTs stabilized with slow- or non-hydrolizable GTP analogs or aldehyde-type cross-linking declined with increasing temperature in a small range of temperatures (20-35°C). Taxol-stabilized microtubule rigidity was reportedly temperature independent. Our lab expanded on this by (1) expanding the temperature range from 0°C to as high as 50°C and (2) by testing single MTs polymerized using three different nucleotides: GTP with Taxol, GMPPCP with Taxol, and GMPCPP. Both GMPPCP and GMPCPP are non-hydrolizable analogs of GTP, and GMPCPP is an established promoter of MT nucleation and growth which enables MT stabilization without taxol. We observed systematic differences between persistence lengths in these three backgrounds but only statistically insignificant variation with temperature for each background. Specifically, we find that MT persistence length is log-normally distributed which not only obscures temperature variability of rigidity in our assays but also likely makes any such variability insignificant for cell function.