Stathmin Strongly Increases the Minus End Catastrophe Frequency and Induces Rapid Treadmilling of Bovine Brain Microtubules at Steady State in Vitro

Tapas Manna #1, Douglas Thrower #1, Herbert P. Miller #1, Patrick Curmi #2, and Leslie Wilson #1
From the #1 Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California
93106 and #2 Laboratoire Structure et Reconnaissance des Biomolecules, EA3637, Universite Evry-Val d'Essonne, rue du pere Jarlan,
91025 Evry, France


Stathmin is a ubiquitous microtubule destabilizing protein that is believed to play an important role linking cell signaling to the regulation of microtubule dynamics. Here we show that stathmin strongly destabilizes microtubule minus ends in vitro at steady state, conditions in which the soluble tubulin and microtubule levels remain constant. Stathmin increased the minus end catastrophe frequency ~13-fold at a stathmin:tubulin molar ratio of 1:5. Stathmin steady-state catastrophe-promoting activity was considerably stronger at the minus ends than at the plus ends. Consistent with its ability to destabilize minus ends, stathmin strongly increased the treadmilling rate of bovine brain microtubules. By immunofluorescence microscopy, we also found that stathmin binds to purified microtubules along their lengths in vitro. Co-sedimentation of purified microtubules polymerized in the presence of a 1:5 initial molar ratio of stathmin to tubulin yielded a binding stoichiometry of 1mol of stathmin per ~14.7 mol of tubulin in the microtubules. The results firmly establish that stathmin can increase the steady-state catastrophe frequency by a direct action on microtubules, and furthermore, they indicate that an important regulatory action of stathmin in cells may be to destabilize microtubule minus ends.
[PDF] [BibTex]
Tapas Manna, Douglas Thrower, Herbert P. Miller, Patrick Curmi and Leslie Wilson,
The Journal of Biological Chemistry, vol. 281, no. 4, pp. 2071–2078, Jan. 2006.
Node ID: 427 , DB ID: 229 , Lab: BIO , Target: Journal