Structural characterization of the DAXX N-terminal helical bundle domain and its complex with Rassf1C.
DAXX is a scaffold protein with diverse roles including transcription and cell cycle regulation. Using NMR spectroscopy, we demonstrate that the C-terminal half of DAXX is intrinsically disordered, whereas a folded domain is present near its N terminus. This domain forms a left-handed four-helix bundle (H1, H2, H4, H5). However, due to a crossover helix (H3), this topology differs from that of the Sin3 PAH domain, which to date has been used as a model for DAXX. The N-terminal residues of the tumor suppressor Rassf1C fold into an amphipathic α helix upon binding this DAXX domain via a shallow cleft along the flexible helices H2 and H5 (K(D) ∼60 μM). Based on a proposed DAXX recognition motif as hydrophobic residues preceded by negatively charged groups, we found that peptide models of p53 and Mdm2 also bound the helical bundle. These data provide a structural foundation for understanding the diverse functions of DAXX.
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T1Z3, Canada.
Eric
E
Escobar-Cabrera
Desmond K W
DK
Lau
Serena
S
Giovinazzi
Alexander M
AM
Ishov
Lawrence P
LP
McIntosh
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D056970:Co-Repressor Proteins; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D018832:Molecular Chaperones; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs / Q000502:physiology; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020539:Sequence Analysis, Protein; D017384:Sequence Deletion; D025521:Tumor Suppressor Proteins / Q000737:chemistry* / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D056970:Co-Repressor Proteins; C106985:DAXX protein, human; D018832:Molecular Chaperones; D046912:Multiprotein Complexes; D050505:Mutant Proteins; D009687:Nuclear Proteins; C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins