Variants of the yeast MAPK Mpk1 are fully functional independently of activation loop phosphorylation

Tal Goshen-Lago, Anat Goldberg-Carp, Dganit Melamed, Ilona Darlyuk-Saadon, Chen Bai, Natalie G. Ahn, Arie Admon, David Engelberg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

MAP kinases of the ERK family are conserved from yeast to humans. Their catalytic activity is dependent on dual phosphorylation of their activation loop's TEY motif, catalyzed by MAPK kinases (MEKs). Here we studied variants of Mpk1, a yeast orthologue of Erk, which is essential for cell wall integrity. Cells lacking MPK1, or the genes encoding the relevant MEKs, MKK1 and MKK2, do not proliferate under cell wall stress, imposed, for example, by caffeine. Mutants of Mpk 1, Mpk1(Y268C) and Mpk1(Y268A), function independently of Mkk1 and Mkk2. We show that these variants are phosphorylated at their activation loop in mkk1Δmkk2Δ and mkk1Δmkk2Δpbs2Δste7Δ cells, suggesting that they autophosphorylate. However, strikingly, when Y268C/A mutations were combined with the kinase-dead mutation, K54R, or mutations at the TEY motif, T190A+Y192F, the resulting proteins still allowed mkk1Δmkk2Δ cells to proliferate under caffeine stress. Mutating the equivalent residue, Tyr-280/Tyr-261, in Erk1/Erk2 significantly impaired Erk1/2's catalytic activity. This study describes the first case in which a MAPK, Erk/Mpk1, imposes a phenotype via a mechanism that is independent of TEY phosphorylation and an unusual case in which an equivalent mutation in a highly conserved domain of yeast and mammalian Erks causes an opposite effect.

Original languageAmerican English
Pages (from-to)2771-2783
Number of pages13
JournalMolecular Biology of the Cell
Volume27
Issue number17
DOIs
StatePublished - 1 Sep 2016

Bibliographical note

Publisher Copyright:
© 2016 Goshen-Lago, Goldberg-Carp, et al.

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