Article

Internal dynamics control activation and activity of the autoinhibited Vav DH domain.

Howard Hughes Medical Institute and Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-8816, USA.
Nature Structural &#38 Molecular Biology (impact factor: 12.71). 07/2008; 15(6):613-8. DOI:10.1038/nsmb.1428 pp.613-8
Source: PubMed

ABSTRACT Protein motions are important to activity, but quantitative relationships between internal dynamics and function are not well understood. The Dbl homology (DH) domain of the proto-oncoprotein and guanine nucleotide exchange factor Vav1 is autoinhibited through interactions between its catalytic surface and a helix from an N-terminal acidic region. Phosphorylation of the helix relieves autoinhibition. Here we show by NMR spectroscopy that the autoinhibited DH domain exists in equilibrium between a ground state, where the active site is blocked by the inhibitory helix, and an excited state, where the helix is dissociated. Across a series of mutants that differentially sample these states, catalytic activity of the autoinhibited protein and its rate of phosphorylation are linearly dependent on the population of the excited state. Thus, internal dynamics are required for and control both basal activity and the rate of full activation of the autoinhibited DH domain.

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Keywords

active site
 
autoinhibited DH domain
 
autoinhibited protein
 
catalytic activity
 
catalytic surface
 
Dbl homology
 
differentially sample
 
excited state
 
full activation
 
ground state
 
guanine nucleotide exchange factor Vav1
 
helix relieves autoinhibition
 
inhibitory helix
 
internal dynamics
 
N-terminal acidic region
 
Phosphorylation
 
Protein motions
 
proto-oncoprotein
 
quantitative relationships
 
states