Crystal Structures of MEK1 Binary and Ternary Complexes with Nucleotides and Inhibitors
Crystal Structures of MEK1 Binary and Ternary Complexes with Nucleotides and Inhibitors
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DOI：
10.1021/bi801898e
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发表时间：
2009-03-31
期刊：
影响因子：
2.9
通讯作者：
Madison, Vincent S.
中科院分区：
文献类型：
--
作者：
Fischmann, Thierry O.;Smith, Catherine K.;Madison, Vincent S.
MEK 1是MAPK信号转导通路的成员，其响应于生长因子和细胞因子。我们已经确定激酶结构域通过蛋白水解切割跨越残基35-382。完整的激酶结构域已经结晶，其X-射线晶体结构作为一个复杂的镁和ATP-γ S在2.1埃确定。与先前公开的截短的激酶结构域的晶体不同，完整结构域的晶体可以作为与核苷酸的二元复合物或作为与核苷酸和多种变构抑制剂之一的三元复合物生长。此外，晶体允许与ATP竞争性抑制剂的共结构的测定。我们描述了非磷酸化MEK 1（npMEK 1）二元复合物与ADP和K252 a，ATP竞争性抑制剂（见表1），在1.9和2.7埃分辨率，分别。npMEK 1（一种核苷酸）和变构非ATP竞争性抑制剂之间的三元复合物也已被解析：ATP-γ S与化合物I，ADP与U 0126或MEK 1临床候选物PD 325089，分别为1.8、2.0和2.5埃。化合物1在结构上类似于PD 325901。这些结构说明了分子水平上各种抑制机制之间的根本差异。残基44-51先前已显示在MEK 1活性中起负调节作用。完整激酶结构域的晶体结构为这些残基的作用提供了结构原理。它们形成螺旋A并通过稳定非活性构象抑制酶活性，其中螺旋C从其活性状态位置被置换。最后，该结构首次提供了一个分子理论基础，解释了MEK突变如何导致心-面-皮肤综合征。
MEK1 is a member of the MAPK signal transduction pathway that responds to growth factors and cytokines. We have determined that the kinase domain spans residues 35-382 by proteolytic cleavage. The complete kinase domain has been crystallized and its X-ray crystal structure as a complex with magnesium and ATP-gamma S determined at 2.1 angstrom. Unlike crystals of a truncated kinase domain previously published, the crystals of the intact domain can be grown either as a binary complex with a nucleotide or as a ternary complex with a nucleotide and one of a multitude of allosteric inhibitors. Further, the crystals allow for the determination of costructures with ATP competitive inhibitors. We describe the structures of nonphosphorylated MEK1 (npMEK1) binary complexes with ADP and K252a, an ATP-competitive inhibitor (see Table 1), at 1.9 and 2.7 angstrom resolution, respectively. Ternary complexes have also been solved between npMEK1, a nucleotide, and an allosteric non-ATP competitive inhibitor: ATP-gamma S with compound I and ADP with either U0126 or the MEK1 clinical candidate PD325089 at 1.8, 2.0, and 2.5 angstrom, respectively. Compound 1 is structurally similar to PD325901. These structures illustrate fundamental differences among various mechanisms of inhibition at the molecular level. Residues 44-51 have previously been shown to play a negative regulatory role in MEK1 activity. The crystal structure of the integral kinase domain provides a structural rationale for the role of these residues. They form helix A and repress enzymatic activity by stabilizing an inactive conformation in which helix C is displaced from its active state position. Finally, the structure provides for the first time a molecular rationale that explains how mutations in MEK may lead to the cardio-facio-cutaneous syndrome.