title: Structural insights into formation of an active signaling complex between Rac and phospholipase C gamma 2.
abstract: Rho family GTPases are important cellular switches and control a number of physiological functions. Understanding the molecular basis of interaction of these GTPases with their effectors is crucial in understanding their functions in the cell. Here we present the crystal structure of the complex of Rac2 bound to the split pleckstrin homology (spPH) domain of phospholipase C-gamma(2) (PLCgamma(2)). Based on this structure, we illustrate distinct requirements for PLCgamma(2) activation by Rac and EGF and generate Rac effector mutants that specifically block activation of PLCgamma(2), but not the related PLCbeta(2) isoform. Furthermore, in addition to the complex, we report the crystal structures of free spPH and Rac2 bound to GDP and GTPgammaS. These structures illustrate a mechanism of conformational switches that accompany formation of signaling active complexes and highlight the role of effector binding as a common feature of Rac and Cdc42 interactions with a variety of effectors.
authors.affiliation: Section of Cell and Molecular Biology , The Institute of Cancer Research, London, UK. tom.bunney@icr.ac.uk
authors.forename: Tom D
authors.initials: TD
authors.lastname: Bunney
authors.forename: Olaniyi
authors.initials: O
authors.lastname: Opaleye
authors.forename: S Mark
authors.initials: SM
authors.lastname: Roe
authors.forename: Petra
authors.initials: P
authors.lastname: Vatter
authors.forename: Rhona W
authors.initials: RW
authors.lastname: Baxendale
authors.forename: Claudia
authors.initials: C
authors.lastname: Walliser
authors.forename: Katy L
authors.initials: KL
authors.lastname: Everett
authors.forename: Michelle B
authors.initials: MB
authors.lastname: Josephs
authors.forename: Carolin
authors.initials: C
authors.lastname: Christow
authors.forename: Fernando
authors.initials: F
authors.lastname: Rodrigues-Lima
authors.forename: Peter
authors.initials: P
authors.lastname: Gierschik
authors.forename: Laurence H
authors.initials: LH
authors.lastname: Pearl
authors.forename: Matilda
authors.initials: M
authors.lastname: Katan
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D051966:Phospholipase C gamma / Q000737:chemistry* / Q000378:metabolism; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013379:Substrate Specificity; D013816:Thermodynamics; D020744:rac GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D000097766:RAC2 GTP-Binding Protein
chemical_list: D004815:Epidermal Growth Factor; D051966:Phospholipase C gamma; D020744:rac GTP-Binding Proteins; D000097766:RAC2 GTP-Binding Protein