title: Dual-site interactions of p53 protein transactivation domain with anti-apoptotic Bcl-2 family proteins reveal a highly convergent mechanism of divergent p53 pathways.
abstract: Molecular interactions between the tumor suppressor p53 and the anti-apoptotic Bcl-2 family proteins play an important role in the transcription-independent apoptosis of p53. The p53 transactivation domain (p53TAD) contains two conserved ΦXXΦΦ motifs (Φ indicates a bulky hydrophobic residue and X is any other residue) referred to as p53TAD1 (residues 15-29) and p53TAD2 (residues 39-57). We previously showed that p53TAD1 can act as a binding motif for anti-apoptotic Bcl-2 family proteins. In this study, we have identified p53TAD2 as a binding motif for anti-apoptotic Bcl-2 family proteins by using NMR spectroscopy, and we calculated the structures of Bcl-X(L)/Bcl-2 in complex with the p53TAD2 peptide. NMR chemical shift perturbation data showed that p53TAD2 peptide binds to diverse members of the anti-apoptotic Bcl-2 family independently of p53TAD1, and the binding between p53TAD2 and p53TAD1 to Bcl-X(L) is competitive. Refined structural models of the Bcl-X(L)·p53TAD2 and Bcl-2·p53TAD2 complexes showed that the binding sites occupied by p53TAD2 in Bcl-X(L) and Bcl-2 overlap well with those occupied by pro-apoptotic BH3 peptides. Taken together with the mutagenesis, isothermal titration calorimetry, and paramagnetic relaxation enhancement data, our structural comparisons provided the structural basis of p53TAD2-mediated interaction with the anti-apoptotic proteins, revealing that Bcl-X(L)/Bcl-2, MDM2, and cAMP-response element-binding protein-binding protein/p300 share highly similar modes of binding to the dual p53TAD motifs, p53TAD1 and p53TAD2. In conclusion, our results suggest that the dual-site interaction of p53TAD is a highly conserved mechanism underlying target protein binding in the transcription-dependent and transcription-independent apoptotic pathways of p53.
authors: Medical Proteomics Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea.
authors: Ji-Hyang
authors: JH
authors: Ha
authors: Jae-Sun
authors: JS
authors: Shin
authors: Mi-Kyung
authors: MK
authors: Yoon
authors: Min-Sung
authors: MS
authors: Lee
authors: Fahu
authors: F
authors: He
authors: Kwang-Hee
authors: KH
authors: Bae
authors: Ho Sup
authors: HS
authors: Yoon
authors: Chong-Kil
authors: CK
authors: Lee
authors: Sung Goo
authors: SG
authors: Park
authors: Yutaka
authors: Y
authors: Muto
authors: Seung-Wook
authors: SW
authors: Chi
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D002151:Calorimetry; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051020:bcl-X Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C491073:BCL2L2 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051020:bcl-X Protein