Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, FL 33620, United States.
Molecular Oncology Department, Moffitt Cancer Center, Tampa, FL 33612, United States.
J Mol Biol. 2022 Nov 30;434(22):167844. doi: 10.1016/j.jmb.2022.167844. Epub 2022 Sep 29.
Autoinhibition of p53 binding to MDMX requires two short-linear motifs (SLiMs) containing adjacent tryptophan (WW) and tryptophan-phenylalanine (WF) residues. NMR spectroscopy was used to show the WW and WF motifs directly compete for the p53 binding site on MDMX and circular dichroism spectroscopy was used to show the WW motif becomes helical when it is bound to the p53 binding domain (p53BD) of MDMX. Binding studies using isothermal titration calorimetry showed the WW motif is a stronger inhibitor of p53 binding than the WF motif when they are both tethered to p53BD by the natural disordered linker. We also investigated how the WW and WF motifs interact with the DNA binding domain (DBD) of p53. Both motifs bind independently to similar sites on DBD that overlap the DNA binding site. Taken together our work defines a model for complex formation between MDMX and p53 where a pair of disordered SLiMs bind overlapping sites on both proteins.
p53 与 MDMX 结合的自动抑制需要两个含有相邻色氨酸（WW）和色氨酸-苯丙氨酸（WF）残基的短线性基序（SLiMs）。NMR 光谱被用来直接显示 WW 和 WF 基序竞争 MDMX 上 p53 的结合位点，圆二色性光谱被用来显示 WW 基序在与 MDMX 的 p53 结合域（p53BD）结合时变成螺旋状。使用等温滴定量热法的结合研究表明，当 WW 基序和 WF 基序都通过天然无序连接子连接到 p53BD 时，WW 基序是比 WF 基序更强的 p53 结合抑制剂。我们还研究了 WW 和 WF 基序如何与 p53 的 DNA 结合域（DBD）相互作用。这两个基序都独立地与 DBD 上的相似位点结合，这些位点与 DNA 结合位点重叠。总之，我们的工作定义了 MDMX 和 p53 之间形成复合物的模型，其中一对无规 SLiMs 结合在两个蛋白质的重叠位点上。
