title: Anti-apoptosis proteins Mcl-1 and Bcl-xL have different p53-binding profiles.
abstract: One of the transcription-independent mechanisms of the tumor suppressor p53 discovered in recent years involves physical interaction between p53 and proteins of the Bcl-2 family. In this paper, significant differences between the interaction of p53 with Mcl-1 and Bcl-xL were demonstrated by NMR spectroscopy and isothermal titration calorimetry. Bcl-xL was found to bind strongly to the p53 DNA-binding domain (DBD) with a dissociation constant (Kd) of ~600 nM, whereas Mcl-1 binds to the p53 DBD weakly with a dissociation constant in the mM range. In contrast, the p53 transactivation domain (TAD) binds weakly to Bcl-xL with a Kd ~ 300-500 μM and strongly to Mcl-1 with a Kd ~ 10-20 μM. NMR titrations indicate that although the p53 TAD binds to the BH3-binding grooves of both Bcl-xL and Mcl-1, Bcl-xL prefers to bind to the first subdomain (TAD1) in the p53 TAD, and Mcl-1 prefers to bind to the second subdomain (TAD2). Therefore, Mcl-1 and Bcl-xL have different p53-binding profiles. This indicates that the detailed interaction mechanisms are different, although both Mcl-1 and Bcl-xL can mediate transcription-independent cytosolic roles of p53. The revealed differences in binding sites and binding affinities should be considered when BH3 mimetics are used in cancer therapy development.
authors: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences , 15 Datun Road, Beijing 100101, China.
authors: Hongwei
authors: H
authors: Yao
authors: Shuofu
authors: S
authors: Mi
authors: Weibin
authors: W
authors: Gong
authors: Jian
authors: J
authors: Lin
authors: Nuo
authors: N
authors: Xu
authors: Sarah
authors: S
authors: Perrett
authors: Bin
authors: B
authors: Xia
authors: Jinfeng
authors: J
authors: Wang
authors: Yingang
authors: Y
authors: Feng
mesh_terms: D000595:Amino Acid Sequence; D002151:Calorimetry; D006801:Humans; D008958:Models, Molecular; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000378:metabolism*; D051020:bcl-X Protein / Q000737:chemistry / Q000378:metabolism*
chemical_list: D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051020:bcl-X Protein