Solution structure of a peptide derived from the oncogenic protein beta-Catenin in its phosphorylated and nonphosphorylated states.
Beta-Catenin plays an essential role in the Wingless/Wnt signaling cascade. Phosphorylation of beta-Catenin in its N-terminal region by the kinase GSK-3beta is required for the interaction with the SCF-beta-TrCP protein complex that targets beta-Catenin for proteasome degradation. In the present work, we used two peptides of 32 amino acids referred to beta-Cat17-48 and P-beta-Cat17-48 for the phosphorylated peptide at the two sites Ser33 and Ser37. Circular dichroism and NMR techniques were used to assess the influence of the phosphorylation. The spectra of the peptides at pH 7.2 were completely assigned. Analysis of the medium-range NOE connectivities indicated that beta-Cat17-48 seems to be only poorly folded. These data are in agreement with the result of structure calculations. P-beta-Cat17-48 possesses two helical segments around the DpSGXXpS motif, which forms a large bent with the phosphate groups pointing out of the structure. On the contrary, beta-Cat17-48 shows less well-defined secondary structures and appears as a more flexible peptide, but adopts in the motif DSGXXS a more compact conformation than P-beta-Cat17-48. Differences in this molecular region suggest that conformational changes of phosphorylated beta-Catenin play an important role for the interaction with the SCF-beta-TrCP protein complex.
Megy
Simon
S
Université René Descartes-Paris V, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601 CNRS, 45 Rue des Saints-Pères, 75270 Paris Cedex 06, France.
Bertho
Gildas
G
Gharbi-Benarous
Josyane
J
Baleux
Françoise
F
Benarous
Richard
R
Girault
Jean-Pierre
JP
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002942:Circular Dichroism; D016384:Consensus Sequence; D003598:Cytoskeletal Proteins / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000302:isolation & purification; D010766:Phosphorylation; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012694:Serine / Q000737:chemistry; D012996:Solutions; D013059:Spectrum Analysis, Raman; D015534:Trans-Activators / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D051176:beta Catenin
D003598:Cytoskeletal Proteins; D006845:Hydrocarbons, Fluorinated; D010455:Peptides; D012996:Solutions; D015534:Trans-Activators; D051176:beta Catenin; D014867:Water; D012694:Serine; C074585:trifluoroethene