Adenylate cyclase activity of TIR1/AFB auxin receptors in plants

Nature. 2022 Nov;611(7934):133-138. doi: 10.1038/s41586-022-05369-7. Epub 2022 Oct 26.


The phytohormone auxin is the major coordinative signal in plant development1, mediating transcriptional reprogramming by a well-established canonical signalling pathway. TRANSPORT INHIBITOR RESPONSE 1 (TIR1)/AUXIN-SIGNALING F-BOX (AFB) auxin receptors are F-box subunits of ubiquitin ligase complexes. In response to auxin, they associate with Aux/IAA transcriptional repressors and target them for degradation via ubiquitination2,3. Here we identify adenylate cyclase (AC) activity as an additional function of TIR1/AFB receptors across land plants. Auxin, together with Aux/IAAs, stimulates cAMP production. Three separate mutations in the AC motif of the TIR1 C-terminal region, all of which abolish the AC activity, each render TIR1 ineffective in mediating gravitropism and sustained auxin-induced root growth inhibition, and also affect auxin-induced transcriptional regulation. These results highlight the importance of TIR1/AFB AC activity in canonical auxin signalling. They also identify a unique phytohormone receptor cassette combining F-box and AC motifs, and the role of cAMP as a second messenger in plants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylyl Cyclases* / genetics
  • Adenylyl Cyclases* / metabolism
  • Arabidopsis Proteins* / genetics
  • Arabidopsis Proteins* / metabolism
  • Arabidopsis* / enzymology
  • Arabidopsis* / metabolism
  • Cyclic AMP / metabolism
  • F-Box Proteins* / genetics
  • F-Box Proteins* / metabolism
  • Gene Expression Regulation, Plant
  • Gravitropism
  • Indoleacetic Acids* / metabolism
  • Indoleacetic Acids* / pharmacology
  • Mutation
  • Plant Growth Regulators / metabolism
  • Plant Growth Regulators / pharmacology
  • Plant Roots / growth & development
  • Receptors, Cell Surface* / genetics
  • Receptors, Cell Surface* / metabolism
  • Second Messenger Systems


  • Adenylyl Cyclases
  • Arabidopsis Proteins
  • F-Box Proteins
  • Indoleacetic Acids
  • Plant Growth Regulators
  • Receptors, Cell Surface
  • TIR1 protein, Arabidopsis
  • Cyclic AMP