Mal3 masks catastrophe events in Schizosaccharomyces pombe microtubules by inhibiting shrinkage and promotingrescue

Miho Katsuki, Douglas R. Drummond, Michael Osei, Robert A. Cross

研究成果: ジャーナルへの寄稿学術誌査読

30 被引用数 (Scopus)


Schizosaccharomyces pombe Mal3 is a member of the EB family of proteins, which are proposed to be core elements in a tiptracking network that regulates microtubule dynamics in cells. How Mal3 itself influences microtubule dynamics is unclear. We tested the effects of full-length recombinant Mal3 on dynamic microtubules assembled in vitro from purified S. pombe tubulin, using dark field video microscopy to avoid fluorescent tagging and data-averaging techniques to improve spatiotemporal resolution. We find that catastrophe occurs stochastically as a fast (<2.2 s) transition from constant speed growth to constant speed shrinkage with a constant probability that is independent of the Mal3 concentration. This implies that Mal3 neither stabilizes nor destabilizes microtubule tips. Mal3 does, however, stabilize the main part of the microtubule lattice, inhibiting shrinkage and increasing the frequency of rescues, consistent with recent models in which Mal3 on the lattice forms stabilizing lateral links between neighboring protofilaments. At high concentrations, Mal3 can entirely block shrinkage and induce very rapid rescue, making catastrophes impossible to detect, which may account for the apparent suppression of catastrophe by Mal3 and other EBs in vivo. Overall, we find that Mal3 stabilizes microtubules not by preventing catastrophe at the microtubule tip but by inhibiting lattice depolymerization and enhancing rescue. We argue that this implies that Mal3 binds microtubules in different modes at the tip and on the lattice.

ジャーナルJournal of Biological Chemistry
出版ステータス出版済み - 10月 23 2009

!!!All Science Journal Classification (ASJC) codes

  • 生化学
  • 分子生物学
  • 細胞生物学


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