Structural details on mdm2-p53 interaction
Structural details on mdm2-p53 interaction
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DOI：
10.1074/jbc.m508578200
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发表时间：
2005-11-18
影响因子：
4.8
通讯作者：
Han, KH
中科院分区：
文献类型：
--
作者：
Chi, SW;Lee, SH;Han, KH
Mdm2是p53的细胞拮抗剂，可保持p53的细胞水平平衡。这两种蛋白通过负调节反馈回路连接，并通过p53反活化结构域（TAD）的残基18 - 26及其位于mdm2 n端100残基结构域的结合口袋形成的假设螺旋相互物理结合（Kussie， P. H., Gorina， S., Marechal， V., Elenbaas， B., Moreau， J., Levine, a . J.和pavleich， N. P. (1996) Science 274, 948 - 953）。在之前的一篇报道中，我们证明了p53 TAD在无mdm2状态下大部分是非结构化的，但除了一个“预先形成的”螺旋外，还包含两个新生的旋转，该螺旋与假定的介导p53-mdm2结合的螺旋相同。在这里，使用异核多维核磁共振方法，我们发现p53 TAD中的两个新生旋转基序，旋转I（残基40 - 45）和旋转II（残基49 - 54）也能够与mdm2结合。特别是，第II轮基序比第I轮基序具有更高的mdm2结合亲和力（类似于20 μ M），并且与螺旋在mdm2中靶向相同的位点。在mdm2结合后，该基序成为一个明确的全螺旋旋转，其由Ile-50、Trp-53和ph -54侧链形成的疏水性面深深插入螺旋结合口袋中。我们的研究结果表明，p53-mdm2的结合比之前认为的更微妙，并且涉及全局接触，如多个“不连续”的最小结构基序，而不是局限于p53 TAD中的一个小螺旋微型结构域。
Mdm2 is a cellular antagonist of p53 that keeps a balanced cellular level of p53. The two proteins are linked by a negative regulatory feedback loop and physically bind to each other via a putative helix formed by residues 18 - 26 of p53 transactivation domain (TAD) and its binding pocket located within the N-terminal 100-residue domain of mdm2 (Kussie, P. H., Gorina, S., Marechal, V., Elenbaas, B., Moreau, J., Levine, A. J., and Pavletich, N. P. ( 1996) Science 274, 948 - 953). In a previous report we demonstrated that p53 TAD in the mdm2-freee state is mostly unstructured but contains two nascent turns in addition to a "preformed" helix that is the same as the putative helix mediating p53-mdm2 binding. Here, using heteronuclear multidimensional NMR methods, we show that the two nascent turn motifs in p53 TAD, turn I ( residues 40 - 45) and turn II ( residues 49 - 54), are also capable of binding to mdm2. In particular, the turn II motif has a higher mdm2 binding affinity ( similar to 20 mu M) than the turn I and targets the same site in mdm2 as the helix. Upon mdm2 binding this motif becomes a well defined full helix turn whose hydrophobic face formed by the side chains of Ile-50, Trp-53, and Phe-54 inserts deeply into the helix binding pocket. Our results suggest that p53-mdm2 binding is subtler than previously thought and involves global contacts such as multiple "non-contiguous" minimally structured motifs instead of being localized to one small helix mini-domain in p53 TAD.