Activation of Arabidopsis MAPK kinase kinase (AtMEKK1) and induction of AtMEKK1-AtMEK1 pathway by wounding

Planta. 2006 Mar;223(4):708-13. doi: 10.1007/s00425-005-0126-7. Epub 2005 Oct 7.


We have constructed a series of deletion mutants of Arabidopsis MAPK kinase kinase (AtMEKK1) and obtained a constitutively active mutant, AtMEKK1Delta166, which lacks in self-inhibitory sequence of N-terminal 166 amino acids but still has substrate specificity. AtMEKK1Delta166 predominantly phosphorylates AtMEK1, an Arabidopsis MAPKK, but not its double mutant (AtMEK1T218A/S224E), suggesting that Thr-218 and Ser-224 are the phosphorylation sites. In wounded seedlings, AtMEKK1 was activated and phosphorylated its downstream AtMEK1. Furthermore, analysis using anti-AtMEKK1 and anti-AtMEK1 antibodies revealed that the interaction between the two proteins was signal dependent. These results suggest the presence of AtMEKK1-AtMEK1 pathway induced by wounding.

MeSH terms

  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Enzyme Activation
  • Gene Expression Regulation, Plant
  • MAP Kinase Kinase 1 / genetics
  • MAP Kinase Kinase 1 / metabolism*
  • MAP Kinase Kinase Kinase 1 / genetics
  • MAP Kinase Kinase Kinase 1 / metabolism*
  • MAP Kinase Signaling System / physiology*
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism
  • Phosphorylation
  • Plant Diseases*
  • Plant Leaves / metabolism
  • Seedlings / metabolism


  • Arabidopsis Proteins
  • AtMPK4 protein, Arabidopsis
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase Kinase 1
  • MAP Kinase Kinase 1
  • MEK1 protein, Arabidopsis