Baskin Alexey, Soudah Nadine, Gilad Nechama, Halevi Neriya, Darlyuk-Saadon Ilona, Schoffman Hanan, Engelberg David
Department of Biological Chemistry, The Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel.
Department of Biological Chemistry, The Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel; Singapore-HUJ Alliance for Research and Enterprise, Mechanisms of Liver Inflammatory Diseases Program, National University of Singapore, Singapore.
J Biol Chem. 2025 Apr 11;301(6):108509. doi: 10.1016/j.jbc.2025.108509.
The extracellular-activated kinases 1 & 2 (Erk1/2) are catalytically active when dually phosphorylated on a TEY motif located at the activation loop. In human patients with cardiac hypertrophy, Erk1/2 are phosphorylated on yet another activation loop's residue, T207/188. Intrinsically active variants of Erk1/2, mutated at R84/65, are also (auto)phosphorylated on T207/188. It is not known whether T207/188 phosphorylation is restricted to these cases, nor how it affects Erks' activity. We report that T207/188 phosphorylation is not rare, as we found that: 1) All known auto-activated Erk1/2 variants are phosphorylated on T207/188. 2) It occurs in various cell lines and mouse tissues. 3) It is extremely high in patients with skeletal muscle atrophies or myopathies. We propose that T207/188 controls the permissiveness of the TEY motif for phosphorylation because T207/188-mutated Erk1/2 and the yeast Erk/Mpk1 were efficiently dually phosphorylated when expressed in HEK293 or yeast cells, respectively. The T207/188-mutated Mpk1 was not TEY-phosphorylated in cells knocked out for MEKs, suggesting that its enhanced phosphorylation in wild-type cells is MEK-dependent. Thus, as T207/188-mutated Erk1/2 and Mpk1 recruit MEKs, the role of T207/188 is to impede MEKs' ability to phosphorylate Erks. T207/188 also impedes autophosphorylation as recombinant Erk2 mutated at T188 is spontaneously autophosphorylated, although exclusively on Y185. The role of T207/188 in regulating activation loop phosphorylation may be common to most Ser/Thr kinases, as 86% of them (in the human kinome) possess T207/188 orthologs, and 160 of them were already reported to be phosphorylated on this residue.
细胞外激活激酶1和2（Erk1/2）在位于激活环的TEY基序上发生双磷酸化时具有催化活性。在患有心脏肥大的人类患者中，Erk1/2在另一个激活环的残基T207/188上发生磷酸化。在R84/65处发生突变的Erk1/2固有活性变体也在T207/188上（自）磷酸化。尚不清楚T207/188磷酸化是否仅限于这些情况，也不清楚它如何影响Erk的活性。我们报告称，T207/188磷酸化并不罕见，因为我们发现：1）所有已知的自激活Erk1/2变体都在T207/188上磷酸化。2）它发生在各种细胞系和小鼠组织中。3）在患有骨骼肌萎缩或肌病的患者中其水平极高。我们提出，T207/188控制TEY基序磷酸化的允许性，因为当分别在HEK293或酵母细胞中表达时，T207/188突变的Erk1/2和酵母Erk/Mpk1能有效地进行双磷酸化。在敲除MEK的细胞中，T207/188突变的Mpk1未发生TEY磷酸化，这表明其在野生型细胞中增强的磷酸化是MEK依赖性的。因此，由于T207/188突变的Erk1/2和Mpk1招募MEK，T207/188的作用是阻碍MEK对Erk进行磷酸化的能力。T207/188也阻碍自磷酸化，因为在T188处发生突变的重组Erk2会自发自磷酸化，尽管仅在Y185上。T207/188在调节激活环磷酸化中的作用可能在大多数丝氨酸/苏氨酸激酶中都很常见，因为其中86%（在人类激酶组中）具有T207/188直系同源物，并且已经报道其中160种在该残基上发生了磷酸化。
