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Mechanistic Origin of Microtubule Dynamic Instability and Its Modulation by EB Proteins

Rui Zhang1, Gregory M Alushin2, Alan Brown3

  • 1Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.

Cell
|August 4, 2015
PubMed

Insights

End-binding proteins (EB) regulate microtubule dynamics by interacting with tubulin structures during GTP hydrolysis. These interactions influence microtubule lattice arrangements and growth, explaining EB protein behavior at microtubule ends.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Cell Biology

Background:

  • Microtubule (MT) dynamic instability is crucial for cellular processes.
  • GTP hydrolysis and microtubule-associated proteins (MAPs), like EB proteins, regulate MT dynamics.

Purpose of the Study:

  • To elucidate the structural mechanisms by which EB proteins modulate microtubule dynamics.

Main Methods:

  • Six cryo-electron microscopy (cryo-EM) structures of microtubules were determined at high resolution (≤3.5 Å).
  • Structures included microtubules bound to GMPCPP, GTPγS, or GDP, and decorated with kinesin or copolymerized with EB3.

Main Results:

  • Identified subtle conformational changes in α-tubulin during GTP hydrolysis, leading to global lattice rearrangements and strain.
  • Observed that EB3 binding to GTPγS-MTs results in a compacted lattice with distinct twist compared to GDP-MTs.
  • Demonstrated that EB3 promotes rapid hydrolysis of GMPCPP, suggesting a role in recognizing intermediate states.

Conclusions:

  • EB proteins modulate structural transitions at growing microtubule ends by interacting with intermediate states formed during GTP hydrolysis.
  • These findings explain the end-tracking behavior of EBs and their influence on microtubule dynamics.

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