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Gene Review

MPK4  -  mitogen-activated protein kinase 4

Arabidopsis thaliana

Synonyms: ATMPK4, F2N1.1, F2N1_1, MAP kinase 4, MAPK4
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Disease relevance of ATMPK4

  • Intriguingly, in contrast to the mpk4 mutant, mkk1 shows no morphological anomalies and is compromised in resistance to both virulent and avirulent Pseudomonas syringae strains [1].
  • We show that the two double-mutant proteins replacing Thr-218/Ser-224 and Ser-220/Ser-224 by Glu expressed in Escherichia coli show a constitutive activity to phosphorylate the Thr and Tyr residues of the kinase-negative mutant of an Arabidopsis MAPK, named ATMPK4, in vitro [2].

High impact information on ATMPK4

  • Transposon inactivation of Arabidopsis MAP kinase 4 produced the mpk4 mutant exhibiting constitutive systemic acquired resistance (SAR) including elevated salicylic acid (SA) levels, increased resistance to virulent pathogens, and constitutive pathogenesis-related gene expression shown by Northern and microarray hybridizations [3].
  • In contrast, mkk2 null plants were impaired in MPK4 and MPK6 activation and were hypersensitive to salt and cold stress [4].
  • MKS1 may therefore contribute to MPK4-regulated defense activation by coupling the kinase to specific WRKY transcription factors [5].
  • The Arabidopsis MPK4 gene appears to negatively regulate salicylic acid-mediated defense responses and positively regulate jasmonic acid-induced responses [6].
  • Overall, our data defines MPK4 as downstream target of MEKK1 and show that MEKK1 functions in integrating ROS homeostasis with plant development and hormone signaling [7].

Biological context of ATMPK4


Anatomical context of ATMPK4

  • The wild-type ATMPK4 was also phosphorylated by the active mutants of AtMEK1 and showed a high protein kinase activity toward myelin basic proteins [2].

Associations of ATMPK4 with chemical compounds

  • MEKK1 kinase activity and protein stability was regulated by H(2)O(2) in a proteasome-dependent manner and mekk1 plants were compromised in ROS-induced MAPK MPK4 activation [7].
  • In agreement with the concept that ROS negatively regulates auxin responses in plants, mekk1 and mpk4 mutants show reduced expression of several auxin-inducible marker genes [7].
  • Activation of ATMPK4 and ATMPK6 was associated with tyrosine phosphorylation but not with the amounts of mRNA or protein [8].
  • This phosphorylation occurred principally on threonine (Thr) residues and resulted in elevated ATMPK4 kinase activity [11].
  • However, treatments with catalase, which removes H(2)O(2), or diphenylene iodonium, which inhibits superoxide and H(2)O(2) production, do not inhibit harpin-induced activation of AtMPK4 or AtMPK6 [10].

Regulatory relationships of ATMPK4


Other interactions of ATMPK4

  • Whereas mpk3 and mpk6 knock out plants showed no defects in development or changes in redox control genes, mpk4 null mutant shared several phenotypic and transcript profile features with mekk1 plants [7].
  • Furthermore, AtMEK1 immunoprecipitated from Arabidopsis seedlings stimulated with wounding, cold, drought, and high salt showed an elevated protein kinase activity toward the kinase-negative ATMPK4, while the amounts of the AtMEK1 protein did not change significantly [2].
  • Tyr dephosphorylation by the Arabidopsis Tyr-specific phosphatase AtPTP1 resulted in an almost complete loss of ATMPK4 activity [11].
  • This proposed role is consistent with the recent finding that WRKY25 is a substrate of Arabidopsis MAP kinase 4, a repressor of SA-dependent defense responses [13].


  1. The Arabidopsis MAP kinase kinase MKK1 participates in defence responses to the bacterial elicitor flagellin. M??sz??ros, T., Helfer, A., Hatzimasoura, E., Magyar, Z., Serazetdinova, L., Rios, G., Bard??czy, V., Teige, M., Koncz, C., Peck, S., B??gre, L. Plant J. (2006) [Pubmed]
  2. Activation of AtMEK1, an Arabidopsis mitogen-activated protein kinase kinase, in vitro and in vivo: analysis of active mutants expressed in E. coli and generation of the active form in stress response in seedlings. Matsuoka, D., Nanmori, T., Sato, K., Fukami, Y., Kikkawa, U., Yasuda, T. Plant J. (2002) [Pubmed]
  3. Arabidopsis map kinase 4 negatively regulates systemic acquired resistance. Petersen, M., Brodersen, P., Naested, H., Andreasson, E., Lindhart, U., Johansen, B., Nielsen, H.B., Lacy, M., Austin, M.J., Parker, J.E., Sharma, S.B., Klessig, D.F., Martienssen, R., Mattsson, O., Jensen, A.B., Mundy, J. Cell (2000) [Pubmed]
  4. The MKK2 pathway mediates cold and salt stress signaling in Arabidopsis. Teige, M., Scheikl, E., Eulgem, T., Dóczi, R., Ichimura, K., Shinozaki, K., Dangl, J.L., Hirt, H. Mol. Cell (2004) [Pubmed]
  5. The MAP kinase substrate MKS1 is a regulator of plant defense responses. Andreasson, E., Jenkins, T., Brodersen, P., Thorgrimsen, S., Petersen, N.H., Zhu, S., Qiu, J.L., Micheelsen, P., Rocher, A., Petersen, M., Newman, M.A., Bjørn Nielsen, H., Hirt, H., Somssich, I., Mattsson, O., Mundy, J. EMBO J. (2005) [Pubmed]
  6. Mapping out the roles of MAP kinases in plant defense. Innes, R.W. Trends Plant Sci. (2001) [Pubmed]
  7. A Mitogen-activated Protein Kinase Kinase Kinase Mediates Reactive Oxygen Species Homeostasis in Arabidopsis. Nakagami, H., Soukupov??, H., Schikora, A., Z??rsky, V., Hirt, H. J. Biol. Chem. (2006) [Pubmed]
  8. Various abiotic stresses rapidly activate Arabidopsis MAP kinases ATMPK4 and ATMPK6. Ichimura, K., Mizoguchi, T., Yoshida, R., Yuasa, T., Shinozaki, K. Plant J. (2000) [Pubmed]
  9. MEKK1 Is Required for MPK4 Activation and Regulates Tissue-specific and Temperature-dependent Cell Death in Arabidopsis. Ichimura, K., Casais, C., Peck, S.C., Shinozaki, K., Shirasu, K. J. Biol. Chem. (2006) [Pubmed]
  10. Harpin induces activation of the Arabidopsis mitogen-activated protein kinases AtMPK4 and AtMPK6. Desikan, R., Hancock, J.T., Ichimura, K., Shinozaki, K., Neill, S.J. Plant Physiol. (2001) [Pubmed]
  11. ATMPK4, an Arabidopsis homolog of mitogen-activated protein kinase, is activated in vitro by AtMEK1 through threonine phosphorylation. Huang, Y., Li, H., Gupta, R., Morris, P.C., Luan, S., Kieber, J.J. Plant Physiol. (2000) [Pubmed]
  12. Arabidopsis MAP kinase 4 regulates salicylic acid- and jasmonic acid/ethylene-dependent responses via EDS1 and PAD4. Brodersen, P., Petersen, M., Bjørn Nielsen, H., Zhu, S., Newman, M.A., Shokat, K.M., Rietz, S., Parker, J., Mundy, J. Plant J. (2006) [Pubmed]
  13. Functional analysis of Arabidopsis WRKY25 transcription factor in plant defense against Pseudomonas syringae. Zheng, Z., Mosher, S.L., Fan, B., Klessig, D.F., Chen, Z. BMC Plant Biol. (2007) [Pubmed]
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