Tubulin oligomers and microtubule oscillations. Antagonistic role of microtubule stabilizers and destabilizers.
Several types of non-equilibrium phenomena have been observed in microtubule polymerization, including dynamic instability, assembly overshoot and oscillations. They can be interpreted in terms of interactions between tubulin subunits (= alpha, beta heterodimers), microtubules, and a third state, oligomers, which represent intermediates between microtubule disassembly and the regeneration of assembly-competent subunits by GTP. Here we examine the role of oligomers by varying conditions that stabilize or destabilize microtubules and/or oligomers. By varying their ratio one can drive tubulin assembly either into steady-state microtubules or oligomers. These regimens of assembly conditions are separated by a region where microtubules oscillate. The oscillations can be simulated by computer modelling, based on a reaction scheme involving the three states of tubulin and nucleotide exchange on tubulin subunits, but not on microtubules or oligomers.
Lange
G
G
Max-Planck Unit for Structural Molecular Biology, Hamburg, Federal Republic of Germany.
Mandelkow
E M
EM
Jagla
A
A
Mandelkow
E
E
D002118:Calcium / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003198:Computer Simulation; D006153:Guanosine Diphosphate / Q000032:analysis; D006160:Guanosine Triphosphate / Q000032:analysis*; D008274:Magnesium / Q000494:pharmacology; D008870:Microtubules / Q000032:analysis*; D009991:Oscillometry; D011108:Polymers / Q000032:analysis; D012542:Scattering, Radiation; D014404:Tubulin / Q000032:analysis*; D014965:X-Rays
D011108:Polymers; D014404:Tubulin; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D008274:Magnesium; D002118:Calcium