title: Structure of the complex of Cdc42Hs with a peptide derived from P-21 activated kinase.
abstract: Cdc42Hs is a member of the Ras superfamily of GTPases and initiates a cascade that begins with the activation of several kinases, including p21-activated kinase (PAK). We have previously used a 46 amino acid fragment of PAK (PBD46) to define the binding surface on Cdc42Hs [Guo et al. (1998) Biochemistry 37, 14030-14037]. Here we describe the three-dimensional solution structure of the Cdc42Hs. GMPPCP-PBD46 complex. Heteronuclear NMR methods were used to assign resonances in the complex, and approximately 2400 distance and dihedral restraints were used to calculate a set of 20 structures using a combination of distance geometry, simulated annealing, and chemical shift and Ramachandran refinement. The overall structure of Cdc42Hs in the complex differs from the uncomplexed structure in two major aspects: (1) the first alpha helix is reoriented to accommodate the binding of the peptide and (2) the regions corresponding to switch I and switch II are less disordered. As suggested by our previous work (Guo et al., 1998) and similar to the complex between Cdc42Hs and fACK [Mott et al. (1999) Nature 399, 384-388], PBD46 forms an intermolecular beta-sheet with beta2 of Cdc42Hs and contacts both switch I and switch II. The extensive binding surface between PBD46 and Cdc42Hs can account for both the high affinity of the complex and the inhibition by PBD46 of GTP hydrolysis.
authors.affiliation: Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA.
authors.forename: D
authors.initials: D
authors.lastname: Gizachew
authors.forename: W
authors.initials: W
authors.lastname: Guo
authors.forename: K K
authors.initials: KK
authors.lastname: Chohan
authors.forename: M J
authors.initials: MJ
authors.lastname: Sutcliffe
authors.forename: R E
authors.initials: RE
authors.lastname: Oswald
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D011505:Protein-Tyrosine Kinases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; C081345:Cdc42Hs-associated kinase; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases