A conserved arginine within the αC-helix of Erk1/2 is a latch of autoactivation and of oncogenic capabilities

Nadine Soudah, Alexey Baskin, Karin Smorodinsky-Atias, Jonah Beenstock, Yifat Ganon, Ruchama Hayouka, Mohammed Aboraya, Oded Livnah, Ronit Ilouz, David Engelberg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Eukaryotic protein kinases (EPKs) adopt an active conformation following phosphorylation of a particular activation loop residue. Most EPKs spontaneously autophosphorylate this residue. While structure–function relationships of the active conformation are essentially understood, those of the “prone-to-autophosphorylate” conformation are unclear. Here, we propose that a site within the αC-helix of EPKs, occupied by Arg in the mitogen-activated protein kinase (MAPK) Erk1/2 (Arg84/65), impacts spontaneous autophosphorylation. MAPKs lack spontaneous autoactivation, but we found that converting Arg84/65 of Erk1/2 to various residues enables spontaneous autophosphorylation. Furthermore, Erk1 molecules mutated in Arg84 are oncogenic. Arg84/65 thus obstructs the adoption of the “prone-to-autophosphorylate” conformation. All MAPKs harbor an Arg that is equivalent to Arg84/65 of Erks, whereas Arg is rarely found at the equivalent position in other EPKs. We observed that Arg84/65 of Erk1/2 interacts with the DFG motif, suggesting that autophosphorylation may be inhibited by the Arg84/65–DFG interactions. Erk1/2s mutated in Arg84/65 autophosphorylate not only the TEY motif, known as critical for catalysis, but also on Thr207/188. Our MS/MS analysis revealed that a large proportion of the Erk2R65H population is phosphorylated on Thr188 or on Tyr185 + Thr188, and a small fraction is phosphorylated on the TEY motif. No molecules phosphorylated on Thr183 + Thr188 were detected. Thus, phosphorylation of Thr183 and Thr188 is mutually exclusive suggesting that not only TEY-phosphorylated molecules are active but perhaps also those phosphorylated on Tyr185 + Thr188. The effect of mutating Arg84/65 may mimic a physiological scenario in which allosteric effectors cause Erk1/2 activation by autophosphorylation.

Original languageAmerican English
Article number105072
JournalJournal of Biological Chemistry
Volume299
Issue number9
DOIs
StatePublished - Sep 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors

Keywords

  • ERK
  • MAP kinase
  • activation loop
  • active variants
  • autophosphorylation
  • eukaryotic protein kinases

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