Regulation of ethylene gas biosynthesis by the Arabidopsis ETO1 protein

Nature. 2004 Apr 29;428(6986):945-50. doi: 10.1038/nature02516.


Ethylene gas is used as a hormone by plants, in which it acts as a critical growth regulator. Its synthesis is also rapidly evoked in response to a variety of biotic and abiotic stresses. The Arabidopsis ethylene-overproducer mutants eto2 and eto3 have previously been identified as having mutations in two genes, ACS5 and ACS9, respectively; these encode isozymes of 1-aminocyclopropane-1-carboxylic acid synthase (ACS), which catalyse the rate-limiting step in ethylene biosynthesis. Here we report that another ethylene-overproducer mutation, eto1, is in a gene that negatively regulates ACS activity and ethylene production. The ETO1 protein directly interacts with and inhibits the enzyme activity of full-length ACS5 but not of a truncated form of the enzyme, resulting in a marked accumulation of ACS5 protein and ethylene. Overexpression of ETO1 inhibited induction of ethylene production by the plant growth regulator cytokinin, and promoted ACS5 degradation by a proteasome-dependent pathway. ETO1 also interacts with CUL3, a constituent of ubiquitin ligase complexes in which we propose that ETO1 serves as a substrate-specific adaptor protein. ETO1 thus has a dual mechanism, inhibiting ACS enzyme activity and targeting it for protein degradation. This permits rapid modulation of the concentration of ethylene.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cysteine Endopeptidases / metabolism
  • Cytokinins / pharmacology
  • Ethylenes / biosynthesis*
  • Ethylenes / metabolism
  • Genes, Plant / genetics
  • Genetic Complementation Test
  • Lyases / chemistry
  • Lyases / metabolism
  • Models, Biological
  • Molecular Sequence Data
  • Multienzyme Complexes / metabolism
  • Proteasome Endopeptidase Complex
  • Protein Binding


  • Arabidopsis Proteins
  • Cytokinins
  • ETO1 protein, Arabidopsis
  • Ethylenes
  • Multienzyme Complexes
  • ethylene
  • Cysteine Endopeptidases
  • Proteasome Endopeptidase Complex
  • Lyases
  • 1-aminocyclopropanecarboxylate synthase

Associated data

  • GENBANK/AY572791
  • GENBANK/AY572792
  • GENBANK/AY572793