STD and TRNOESY NMR studies on the conformation of the oncogenic protein beta-catenin containing the phosphorylated motif DpSGXXpS bound to the beta-TrCP protein.
beta-TrCP is the F-box protein component of an Skp1/Cul1/F-box (SCF)-type ubiquitin ligase complex. Biochemical studies have suggested that beta-TrCP targets the oncogenic protein beta-catenin for ubiquitination and followed by proteasome degradation. To further elucidate the basis of this interaction, a complex between a 32-residue peptide from beta-catenin containing the phosphorylated motif DpSGXXpS (P-beta-Cat17-48) and beta-TrCP was studied using Saturation Transfer Difference (STD) Nuclear Magnetic Resonance (NMR) experiments. These experiments make it possible to identify the binding epitope of a ligand at atomic resolution. An analysis of STD spectra provided clear evidence that only a few of the 32 residues receive the largest saturation transfer. In particular, the amide protons of the residues in the phosphorylated motif appear to be in close contact to the amino acids of the beta-TrCP binding pocket. The amide and aromatic protons of the His24 and Trp25 residues also receive a significant saturation transfer. These findings are in keeping with a recently published x-ray structure of a shorter beta-catenin fragment with the beta-TrCP1-Skp1 complex and with the earlier findings from mutagenesis and activity assays. To better characterize the ligand-protein interaction, the bound conformation of the phosphorylated beta-catenin peptide was obtained using TRansfer Nuclear Overhauser Effect SpectroscopY (TRNOESY) experiments. Finally, we obtained the bound structure of the phosphorylated peptide showing the protons identified by STD NMR as exposed in close proximity to the molecule surface.
Megy
Simon
S
Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques (UMR 8601 CNRS), Université René Descartes-Paris V, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France.
Bertho
Gildas
G
Gharbi-Benarous
Josyane
J
Evrard-Todeschi
Nathalie
N
Coadou
Gael
G
Ségéral
Emmanuel
E
Iehle
Catherine
C
Quéméneur
Eric
E
Benarous
Richard
R
Girault
Jean-Pierre
JP
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D003598:Cytoskeletal Proteins / Q000737:chemistry*; D005982:Glutathione Transferase / Q000378:metabolism; D006639:Histidine / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011522:Protons; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D012984:Software; D013997:Time Factors; D015534:Trans-Activators / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry; D014965:X-Rays; D051176:beta Catenin; D044844:beta-Transducin Repeat-Containing Proteins / Q000737:chemistry*
C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D008024:Ligands; D010455:Peptides; D011522:Protons; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D051176:beta Catenin; D044844:beta-Transducin Repeat-Containing Proteins; D006639:Histidine; D014364:Tryptophan; D005982:Glutathione Transferase