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Model for stathmin/OP18 binding to tubulin
G Wallon1, J Rappsilber, M Mann
1Structural Biology Program, EMBL, Meyerhofstrasse 1, 69117 Heidelberg, Germany. wallon@embl-heidelberg.de
The EMBO Journal
|January 19, 2000
Summary
Stathmin/OP18 regulates microtubule dynamics by binding alpha-tubulin. Full-length stathmin/OP18 inhibits tubulin polymerization by sequestering dimers, while truncated forms show reduced activity.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Stathmin/OP18 is a key phosphoprotein regulating microtubule dynamics.
- The protein lacks a defined 3D structure, comprising an N-terminus, H1, and H2 regions.
Purpose of the Study:
- To investigate the structure-function relationship of stathmin/OP18 in microtubule regulation.
- To determine the binding sites and mechanism of stathmin/OP18 interaction with alpha-tubulin.
Main Methods:
- Analysis of full-length and truncated stathmin/OP18 constructs.
- Biochemical assays to assess tubulin polymerization inhibition.
- Mass spectrometry to identify binding interfaces with alpha-tubulin.
Main Results:
- Full-length stathmin/OP18 and H1+H2 inhibit tubulin polymerization; H1+N-terminus is less effective.
- Individual regions do not inhibit polymerization but cross-link to alpha-tubulin.
- Full-length stathmin/OP18 binds alpha-tubulin near helix 10, sequestering dimers and potentially linking heterodimers.
- Stathmin/OP18 lacking the N-terminus binds one alpha-tubulin molecule, preventing polymerization.
Conclusions:
- Stathmin/OP18's N-terminus is crucial for potent inhibition of tubulin polymerization.
- The protein's distinct regions contribute differentially to microtubule dynamics regulation.
- Stathmin/OP18 acts by sequestering tubulin dimers and potentially cross-linking heterodimers.