Mashhoon N, DeMaggio A J, Tereshko V, Bergmeier S C, Egli M, Hoekstra M F, Kuret J
Center for Biotechnology, Ohio State University College of Medicine, Columbus, Ohio 43210, ICOS Corporation, Bothell, Washington 98021, USA.
J Biol Chem. 2000 Jun 30;275(26):20052-60. doi: 10.1074/jbc.M001713200.
Members of the casein kinase-1 family of protein kinases play an essential role in cell regulation and disease pathogenesis. Unlike most protein kinases, they appear to function as constitutively active enzymes. As a result, selective pharmacological inhibitors can play an important role in dissection of casein kinase-1-dependent processes. To address this need, new small molecule inhibitors of casein kinase-1 acting through ATP-competitive and ATP-noncompetitive mechanisms were isolated on the basis of in vitro screening. Here we report the crystal structure of 3-[(2,4,6-trimethoxyphenyl) methylidenyl]-indolin-2-one (IC261), an ATP-competitive inhibitor with differential activity among casein kinase-1 isoforms, in complex with the catalytic domain of fission yeast casein kinase-1 refined to a crystallographic R-factor of 22.4% at 2.8 A resolution. The structure reveals that IC261 stabilizes casein kinase-1 in a conformation midway between nucleotide substrate liganded and nonliganded conformations. We propose that adoption of this conformation by casein kinase-1 family members stabilizes a delocalized network of side chain interactions and results in a decreased dissociation rate of inhibitor.
酪蛋白激酶-1家族的蛋白激酶成员在细胞调控和疾病发病机制中发挥着重要作用。与大多数蛋白激酶不同，它们似乎作为组成型活性酶发挥作用。因此，选择性药理抑制剂在剖析酪蛋白激酶-1依赖性过程中可发挥重要作用。为满足这一需求，基于体外筛选分离出了通过ATP竞争性和ATP非竞争性机制发挥作用的新型酪蛋白激酶-1小分子抑制剂。在此，我们报道了3-[(2,4,6-三甲氧基苯基)亚甲基]-吲哚啉-2-酮（IC261）的晶体结构，IC261是一种在酪蛋白激酶-1亚型中具有不同活性的ATP竞争性抑制剂，它与裂殖酵母酪蛋白激酶-1的催化结构域形成复合物，在2.8埃分辨率下晶体学R因子为22.4%。该结构表明，IC261使酪蛋白激酶-1稳定在核苷酸底物结合构象和未结合构象之间的中间构象。我们提出，酪蛋白激酶-1家族成员采用这种构象可稳定侧链相互作用的离域网络，并导致抑制剂解离速率降低。
