title: Variants of the yeast MAPK Mpk1 are fully functional independently of activation loop phosphorylation.
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 Mpk1, Mpk1(Y268C) and Mpk1(Y268A), function independently of Mkk1 and Mkk2. We show that these variants are phosphorylated at their activation loop in mkk1∆mkk2∆ and mkk1∆mkk2∆pbs2∆ste7∆ 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 mkk1∆mkk2∆ 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.
authors.affiliation: Department of Biological Chemistry, Institute of Life Science, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Tal
authors.initials: T
authors.lastname: Goshen-Lago
authors.affiliation: Department of Biological Chemistry, Institute of Life Science, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Anat
authors.initials: A
authors.lastname: Goldberg-Carp
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: Dganit
authors.initials: D
authors.lastname: Melamed
authors.affiliation: CREATE-NUS-HUJ, Cellular and Molecular Mechanisms of Inflammation Program, National University of Singapore, Singapore 138602 Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456.
authors.forename: Ilona
authors.initials: I
authors.lastname: Darlyuk-Saadon
authors.affiliation: CREATE-NUS-HUJ, Cellular and Molecular Mechanisms of Inflammation Program, National University of Singapore, Singapore 138602 Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456.
authors.forename: Chen
authors.initials: C
authors.lastname: Bai
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309.
authors.forename: Natalie G
authors.initials: NG
authors.lastname: Ahn
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: Arie
authors.initials: A
authors.lastname: Admon
authors.affiliation: Department of Biological Chemistry, Institute of Life Science, Hebrew University of Jerusalem, Jerusalem 91904, Israel CREATE-NUS-HUJ, Cellular and Molecular Mechanisms of Inflammation Program, National University of Singapore, Singapore 138602 Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456 engelber@mail.huji.ac.il MICDE@nus.edu.sg.
authors.forename: David
authors.initials: D
authors.lastname: Engelberg
mesh_terms: D016475:3T3 Cells; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D018929:Cell Culture Techniques; D002473:Cell Wall / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D020935:MAP Kinase Signaling System; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; C072724:SLT2 protein, S cerevisiae; C000609667:MKK1 protein, S cerevisiae; C561307:MKK2 protein, S cerevisiae; D020929:Mitogen-Activated Protein Kinase Kinases