Cell
Volume 140, Issue 2, 22 January 2010, Pages 246-256
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Article
Structural and Energetic Mechanisms of Cooperative Autoinhibition and Activation of Vav1

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Summary

Vav proteins are guanine nucleotide exchange factors (GEFs) for Rho family GTPases. They control processes including T cell activation, phagocytosis, and migration of normal and transformed cells. We report the structure and biophysical and cellular analyses of the five-domain autoinhibitory element of Vav1. The catalytic Dbl homology (DH) domain of Vav1 is controlled by two energetically coupled processes. The DH active site is directly, but weakly, inhibited by a helix from the adjacent Acidic domain. This core interaction is strengthened 10-fold by contacts of the calponin homology (CH) domain with the Acidic, pleckstrin homology, and DH domains. This construction enables efficient, stepwise relief of autoinhibition: initial phosphorylation events disrupt the modulatory CH contacts, facilitating phosphorylation of the inhibitory helix and consequent GEF activation. Our findings illustrate how the opposing requirements of strong suppression of activity and rapid kinetics of activation can be achieved in multidomain systems.

Highlights

► The structure is determined of the five-domain autoinhibitory element of Vav1 ► The Vav1 Dbl homology domain is inhibited by cooperative interdomain interactions ► Inhibition is relieved in stepwise fashion by phosphorylation ► The energetics of multidomain systems enable strong inhibition and rapid activation

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5

These authors contributed equally to this work

6

Present address: Department of Biochemistry, Biophysics, and Molecular Biology, 4210 Molecular Biology Building, Iowa State University, Ames, IA 50011, USA

7

Present address: University of North Carolina, School of Medicine, Chapel Hill, NC 27599, USA