Deactivation of the Arabidopsis brassinosteroid insensitive 1 (BRI1) receptor kinase by autophosphorylation within the glycine-rich loop

Man Ho Oh, Xiaofeng Wang, Steven D. Clouse, Steven C. Huber

Research output: Contribution to journalArticlepeer-review


The activity of the dual-specificity receptor kinase, brassinosteroid insensitive 1 (BRI1), reflects the balance between phosphorylationdependent activation and several potential mechanisms for deactivation of the receptor. In the present report, we elucidate a unique mechanism for deactivation that involves autophosphorylation of serine-891 in the ATP-binding domain. Serine-891 was identified previously as a potential site of autophosphorylation by mass spectrometry, and sequence-specific antibodies and mutagenesis studies now unambiguously establish phosphorylation of this residue. In vivo, phosphorylation of serine-891 increased slowly with time following application of brassinolide (BL) to Arabidopsis seedlings, whereas phosphorylation of threonine residues increased rapidly and then remained constant. Transgenic plants expressing the BRI1(S891A)-Flag-directed mutant have increased hypocotyl and petiole lengths, relative to wild-type BRI1-Flag (both in the bri1-5 background), and accumulate higher levels of the unphosphorylated form of the BES1 transcription factor in response to exogenous BL. In contrast, plants expressing the phosphomimetic S891D-directed mutant are severely dwarfed and do not accumulate unphosphorylated BES1 in response to BL. Collectively, these results suggest that autophosphorylation of serine-891 is one of the deactivation mechanisms that inhibit BRI1 activity and BR signaling in vivo. Many arginine-aspartate (RD)-type leucine-rich repeat receptor-like kinases have a phosphorylatable residue within the ATP-binding domain, suggesting that this mechanism may play a broad role in receptor kinase deactivation.

Original languageEnglish (US)
Pages (from-to)327-332
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number1
StatePublished - Jan 3 2012
Externally publishedYes


  • Modificationspecific antibodies
  • Phosphoserine
  • Phosphotyrosine
  • Signal transduction

ASJC Scopus subject areas

  • General


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