Nature Structural Biology8, 1037 - 1041 (2001)
Published online: 29 October 2001; | doi:10.1038/nsb719
Molecular basis for Rac1 recognition by guanine nucleotide exchange factors
Antoine E. Karnoub1, 2, David K. Worthylake2, Kent L. Rossman1, Wendy Morse Pruitt2, Sharon L. Campbell1, John Sondek1, 2
& Channing J. Der2
1
Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, North Carolina 27599, USA.
2
Department of Pharmacology, University of North Carolina at Chapel Hill, Lineberger Comprehensive Cancer Center, Chapel Hill, North Carolina 27599, USA.
Correspondence should be addressed to Channing J. Der cjder@med.unc.edu
Rho GTPases are activated by a family of guanine nucleotide exchange factors (GEFs) known as Dbl family proteins. The structural basis for how GEFs recognize and activate Rho GTPases is presently ill defined. Here, we utilized the crystal structure of the DH/PH domains of the Rac-specific GEF Tiam1 in complex with Rac1 to determine the structural elements of Rac1 that regulate the specificity of this interaction. We show that residues in the Rac1 2−3 region are critical for Tiam1 recognition. Additionally, we determined that a single Rac1-to-Cdc42 mutation (W56F) was sufficient to abolish Rac1 sensitivity to Tiam1 and allow recognition by the Cdc42-specific DH/PH domains of Intersectin while not impairing Rac1 downstream activities. Our findings identified unique GEF specificity determinants in Rac1 and provide important insights into the mechanism of DH/PH selection of GTPase targets.
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