title: Structural basis for the selective activation of Rho GTPases by Dbl exchange factors.
abstract: Activation of Rho-family GTPases involves the removal of bound GDP and the subsequent loading of GTP, all catalyzed by guanine nucleotide exchange factors (GEFs) of the Dbl-family. Despite high sequence conservation among Rho GTPases, Dbl proteins possess a wide spectrum of discriminatory potentials for Rho-family members. To rationalize this specificity, we have determined crystal structures of the conserved, catalytic fragments (Dbl and pleckstrin homology domains) of the exchange factors intersectin and Dbs in complex with their cognate GTPases, Cdc42 and RhoA, respectively. Structure-based mutagenesis of intersectin and Dbs reveals the key determinants responsible for promoting exchange activity in Cdc42, Rac1 and RhoA. These findings provide critical insight into the structural features necessary for the proper pairing of Dbl-exchange factors with Rho GTPases and now allow for the detailed manipulation of signaling pathways mediated by these oncoproteins in vivo.
authors: Department of Biochemistry and Biophysics, Program in Molecular and Cellular Biophysics, Chapel Hill, North Carolina 27599, USA.
authors: Jason T
authors: JT
authors: Snyder
authors: David K
authors: DK
authors: Worthylake
authors: Kent L
authors: KL
authors: Rossman
authors: Laurie
authors: L
authors: Betts
authors: Wendy M
authors: WM
authors: Pruitt
authors: David P
authors: DP
authors: Siderovski
authors: Channing J
authors: CJ
authors: Der
authors: John
authors: J
authors: Sondek
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry* / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000737:chemistry*; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D000075684:T-Lymphoma Invasion and Metastasis-inducing Protein 1; D020764:cdc42 GTP-Binding Protein / Q000737:chemistry / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000737:chemistry / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000737:chemistry / Q000378:metabolism
chemical_list: D020662:Guanine Nucleotide Exchange Factors; C057811:MCF2 protein, human; D011506:Proteins; D011518:Proto-Oncogene Proteins; D000075684:T-Lymphoma Invasion and Metastasis-inducing Protein 1; C087334:TIAM1 protein, human; D006160:Guanosine Triphosphate; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein