Structural Analysis of 14-3-3 Phosphopeptide Complexes Identifies a Dual Role for the Nuclear Export Signal of 14-3-3 in Ligand Binding

Mol Cell. 1999 Aug;4(2):153-66. doi: 10.1016/s1097-2765(00)80363-9.

Abstract

We have solved the high-resolution X-ray structure of 14-3-3 bound to two different phosphoserine peptides, representing alternative substrate-binding motifs. These structures reveal an evolutionarily conserved network of peptide-protein interactions within all 14-3-3 isotypes, explain both binding motifs, and identify a novel intrachain phosphorylation-mediated loop structure in one of the peptides. A 14-3-3 mutation disrupting Raf signaling alters the ligand-binding cleft, selecting a different phosphopeptide-binding motif and different substrates than the wild-type protein. Many 14-3-3: peptide contacts involve a C-terminal amphipathic alpha helix containing a putative nuclear export signal, implicating this segment in both ligand and Crm1 binding. Structural homology between the 14-3-3 NES structure and those within I kappa B alpha and p53 reveals a conserved topology recognized by the Crm1 nuclear export machinery.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 14-3-3 Proteins
  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Cell Nucleus / metabolism
  • Consensus Sequence
  • Conserved Sequence
  • Crystallography, X-Ray
  • Drosophila
  • Enzyme Inhibitors / chemistry
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Phosphopeptides / chemistry*
  • Phosphopeptides / metabolism
  • Protein Isoforms / chemistry
  • Protein Isoforms / metabolism
  • Protein Structure, Secondary
  • Proteins / chemistry*
  • Proteins / metabolism
  • Saccharomyces cerevisiae
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Tyrosine 3-Monooxygenase*

Substances

  • 14-3-3 Proteins
  • Enzyme Inhibitors
  • Phosphopeptides
  • Protein Isoforms
  • Proteins
  • Tyrosine 3-Monooxygenase