title: The peripheral binding of 14-3-3γ to membranes involves isoform-specific histidine residues.
abstract: Mammalian 14-3-3 protein scaffolds include seven conserved isoforms that bind numerous phosphorylated protein partners and regulate many cellular processes. Some 14-3-3-isoforms, notably γ, have elevated affinity for membranes, which might contribute to modulate the subcellular localization of the partners and substantiate the importance of investigating molecular mechanisms of membrane interaction. By applying surface plasmon resonance we here show that the binding to phospholipid bilayers is stimulated when 14-3-3γ is complexed with its partner, a peptide corresponding to the Ser19-phosphorylated N-terminal region of tyrosine hydroxylase. Moreover, membrane interaction is dependent on salts of kosmotropic ions, which also stabilize 14-3-3γ. Electrostatic analysis of available crystal structures of γ and of the non-membrane-binding ζ-isoform, complemented with molecular dynamics simulations, indicate that the electrostatic potential distribution of phosphopeptide-bound 14-3-3γ is optimal for interaction with the membrane through amphipathic helices at the N-terminal dimerization region. In addition, His158, and especially His195, both specific to 14-3-3γ and located at the convex lateral side, appeared to be pivotal for the ligand induced membrane interaction, as corroborated by site-directed mutagenesis. The participation of these histidine residues might be associated to their increased protonation upon membrane binding. Overall, these results reveal membrane-targeting motifs and give insights on mechanisms that furnish the 14-3-3γ scaffold with the capacity for tuned shuffling from soluble to membrane-bound states.
authors.affiliation: Department of Biomedicine, University of Bergen, Bergen, Norway.
authors.forename: Helene J
authors.initials: HJ
authors.lastname: Bustad
authors.forename: Lars
authors.initials: L
authors.lastname: Skjaerven
authors.forename: Ming
authors.initials: M
authors.lastname: Ying
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Halskau
authors.forename: Anne
authors.initials: A
authors.lastname: Baumann
authors.forename: David
authors.initials: D
authors.lastname: Rodriguez-Larrea
authors.forename: Miguel
authors.initials: M
authors.lastname: Costas
authors.forename: Jarl
authors.initials: J
authors.lastname: Underhaug
authors.forename: Jose M
authors.initials: JM
authors.lastname: Sanchez-Ruiz
authors.forename: Aurora
authors.initials: A
authors.lastname: Martinez
mesh_terms: D048948:14-3-3 Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010748:Phosphopeptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D020033:Protein Isoforms; D055550:Protein Stability; D055672:Static Electricity; D020349:Surface Plasmon Resonance
chemical_list: D048948:14-3-3 Proteins; D008024:Ligands; D010748:Phosphopeptides; D020033:Protein Isoforms; D006639:Histidine