title: 14-3-3 proteins interact with a hybrid prenyl-phosphorylation motif to inhibit G proteins.
abstract: Signaling through G proteins normally involves conformational switching between GTP- and GDP-bound states. Several Rho GTPases are also regulated by RhoGDI binding and sequestering in the cytosol. Rnd proteins are atypical constitutively GTP-bound Rho proteins, whose regulation remains elusive. Here, we report a high-affinity 14-3-3-binding site at the C terminus of Rnd3 consisting of both the Cys241-farnesyl moiety and a Rho-associated coiled coil containing protein kinase (ROCK)-dependent Ser240 phosphorylation site. 14-3-3 binding to Rnd3 also involves phosphorylation of Ser218 by ROCK and/or Ser210 by protein kinase C (PKC). The crystal structure of a phosphorylated, farnesylated Rnd3 peptide with 14-3-3 reveals a hydrophobic groove in 14-3-3 proteins accommodating the farnesyl moiety. Functionally, 14-3-3 inhibits Rnd3-induced cell rounding by translocating it from the plasma membrane to the cytosol. Rnd1, Rnd2, and geranylgeranylated Rap1A interact similarly with 14-3-3. In contrast to the canonical GTP/GDP switch that regulates most Ras superfamily members, our results reveal an unprecedented mechanism for G protein inhibition by 14-3-3 proteins.
authors.affiliation: Randall Division of Cell and Molecular Biophysics, New Hunt's House, King's College London, London, UK.
authors.forename: Philippe
authors.initials: P
authors.lastname: Riou
authors.forename: Svend
authors.initials: S
authors.lastname: Kjær
authors.forename: Ritu
authors.initials: R
authors.lastname: Garg
authors.forename: Andrew
authors.initials: A
authors.lastname: Purkiss
authors.forename: Roger
authors.initials: R
authors.lastname: George
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Cain
authors.forename: Ganka
authors.initials: G
authors.lastname: Bineva
authors.forename: Nicolas
authors.initials: N
authors.lastname: Reymond
authors.forename: Brad
authors.initials: B
authors.lastname: McColl
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Thompson
authors.forename: Nicola
authors.initials: N
authors.lastname: O'Reilly
authors.forename: Neil Q
authors.initials: NQ
authors.lastname: McDonald
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Parker
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Ridley
mesh_terms: D048948:14-3-3 Proteins / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D018360:Crystallography, X-Ray; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D054876:Prenylation; D054730:Protein Interaction Domains and Motifs; D020741:rho GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; C572235:YWHAZ protein, human; C508705:RND3 protein, human; D020741:rho GTP-Binding Proteins