Teufel Daniel P, Freund Stefan M, Bycroft Mark, Fersht Alan R
MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road, Cambridge, UK.
Proc Natl Acad Sci U S A. 2007 Apr 24;104(17):7009-14. doi: 10.1073/pnas.0702010104. Epub 2007 Apr 16.
The transcriptional coactivator p300 binds to and mediates the transcriptional functions of the tetrameric tumor suppressor p53. Both proteins consist of independently folded domains linked by intrinsically disordered sequences. A well studied short sequence of the p53 transactivation domain, p53(15-29), binds weakly to four folded domains of p300 [Taz1/cysteine-histidine-rich region 1 (CH1), Kix, Taz2/CH3, IBiD], with dissociation constants (K(D)) in the 100 muM region. However, we found that a longer N-terminal transactivation domain construct p53(1-57) bound tightly to each p300 domain. Taz2/CH3 had the greatest affinity (K(D) = 27 nM) and competes with the N-terminal domain of Mdm2 for the p53 N terminus. p300 thus can protect the N terminus of p53 against the binding of other proteins. Mutations of p53 that abrogate transactivation (L22Q/W23S, W53Q/F54S) greatly weakened binding to each p300 domain, linking phenotypic defects to weakened coactivator binding. We propose a complex between tetrameric p53 and p300 in which four domains of p300 wrap around the four transactivation domains of p53.
转录共激活因子p300与四聚体肿瘤抑制因子p53结合并介导其转录功能。这两种蛋白质均由通过内在无序序列连接的独立折叠结构域组成。p53反式激活结构域中一个研究充分的短序列p53(15 - 29)与p300的四个折叠结构域[Taz1/富含半胱氨酸 - 组氨酸区域1(CH1)、Kix、Taz2/CH3、IBiD]弱结合，解离常数(K(D))在100 μM范围内。然而，我们发现一个更长的N端反式激活结构域构建体p53(1 - 57)与每个p300结构域紧密结合。Taz2/CH3具有最大亲和力(K(D)= 27 nM)，并与Mdm2的N端结构域竞争p53的N端。因此，p300可以保护p53的N端免受其他蛋白质的结合。消除反式激活的p53突变(L22Q/W23S、W53Q/F54S)极大地削弱了与每个p300结构域的结合，将表型缺陷与共激活因子结合减弱联系起来。我们提出了一种四聚体p53与p300之间的复合物，其中p300的四个结构域围绕p53的四个反式激活结构域。
