Mechanism of Tubulin Oligomers and Single-Ring Disassembly Catastrophe

Asaf Shemesh, Avi Ginsburg, Raviv Dharan, Yael Levi-Kalisman, Israel Ringel, Uri Raviv*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Cold tubulin dimers coexist with tubulin oligomers and single rings. These structures are involved in microtubule assembly; however, their dynamics are poorly understood. Using state-of-the-art solution synchrotron time-resolved small-angle X-ray scattering, we discovered a disassembly catastrophe (half-life of ∼0.1 s) of tubulin rings and oligomers upon dilution or addition of guanosine triphosphate. A slower disassembly (half-life of ∼38 s) was observed following an increase in temperature. Our analysis showed that the assembly and disassembly processes were consistent with an isodesmic mechanism, involving a sequence of reversible reactions in which dimers were rapidly added or removed one at a time, terminated by a 2 order-of-magnitude slower ring-closing/opening step. We revealed how assembly conditions varied the mass fraction of tubulin in each of the coexisting structures, the rate constants, and the standard Helmholtz free energies for closing a ring and for longitudinal dimer-dimer associations.

Original languageAmerican English
Pages (from-to)5246-5252
Number of pages7
JournalJournal of Physical Chemistry Letters
StatePublished - 2022

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