A two-state allosteric model for autoinhibition rationalizes WASP signal integration and targeting

Matthias Buck, Wei Xu, Michael K. Rosen

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

Remodeling of the actin cytoskeleton is controlled by signaling pathways that include the Wiskott-Aldrich syndrome protein (WASP). WASP is regulated by autoinhibition, and the intramolecular contacts that inactivate the protein can be relieved through binding to the Rho-family GTPase Cdc42. Here, we show that the allosteric regulation of WASP can be quantitatively described by a two-state equilibrium between an active, largely unfolded conformation that is able to stimulate the Arp2/3 complex, and an inactive, folded conformation. The model is parameterized by the stability of WASP against unfolding and by the Cdc42 affinities of WASP constructs that mimic the unfolded and folded conformations. The model is consistent with NMR spectra of GTPase-bound WASP, and accurately predicts changes of amide hydrogen exchange behavior and Cdc42 affinity as a function of WASP stability. The results provide a thermodynamic rationale for the GTPase-independent recruitment of WASP and other autoinhibited effectors to their sites of activity. They also explain how basal activity is suppressed and confirm that WASP needs to integrate multiple cooperative inputs for maximal activation. Our analysis suggests that, in general, simple modulation of a two-state equilibrium may determine several regulatory functions, allowing the generation of complex signaling behavior in vivo.

Original languageEnglish (US)
Pages (from-to)271-285
Number of pages15
JournalJournal of Molecular Biology
Volume338
Issue number2
DOIs
StatePublished - Apr 23 2004

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Keywords

  • Allosteric
  • Cytoskeleton/Cdc42 GTPase
  • GBD, GTPase binding domain
  • Signal transduction
  • VCA, verprolin homology region, central hydrophobic and acidic C-terminal region of WASP
  • WASP, Wiskott-Aldrich syndrome protein
  • Wiskott-Aldrich

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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