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Phosphorylation disrupts the central helix in Op18/stathmin and suppresses binding to tubulin

M O Steinmetz1, W Jahnke, H Towbin

  • 12Functional Genomics Area, 1Core Technology Area and 3Oncology Research, Novartis Pharma AG, CH-4002 Basel, Switzerland. michel.steinmetz@psi.ch

EMBO Reports
|June 21, 2001
PubMed

Insights

Phosphorylation of Oncoprotein 18/stathmin (Op18) at Ser63 disrupts its helix structure, reducing tubulin binding and microtubule polymerization inhibition. This provides insights into disordered protein regulation.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Structural Biology

Background:

  • Protein phosphorylation is a key cellular control mechanism.
  • The structural effects of post-translational modifications are not well understood.
  • Oncoprotein 18/stathmin (Op18) is a disordered phosphoprotein regulating microtubule dynamics.

Purpose of the Study:

  • To investigate the structural consequences of Op18 phosphorylation.
  • To understand how phosphorylation affects Op18's interaction with tubulin and microtubule polymerization.

Main Methods:

  • The study focused on Op18 phosphorylation at Ser63.
  • Structural analysis of the helix initiation site.

Main Results:

  • Phosphorylation of Op18 at Ser63 disrupts a transient amphipathic helix.
  • The phosphoryl group reduces tubulin binding affinity by 10-fold.
  • MT polymerization inhibition activity of Op18's C-terminal domain is suppressed.

Conclusions:

  • Phosphorylation within a regular secondary structure element impacts Op18 function.
  • Findings aid in predicting phosphorylation sites and understanding disordered protein behavior.

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