Interaction of Arabidopsis BRASSINOSTEROID-INSENSITIVE 1 receptor kinase with a homolog of mammalian TGF-β receptor interacting protein

Hashimul Ehsan, William Keith Ray, Brett Phinney, Xiaofeng Wang, Steven C. Huber, Steven D. Clouse

Research output: Contribution to journalArticle

Abstract

Brassinosteroids (BRs) regulate multiple aspects of plant growth and development and require an active BRASSINOSTEROID-INSENSITIVE 1 (BRI1) receptor serine/threonine kinase for hormone perception and signal transduction. In mammals, the transforming growth factor-beta (TGF-β) family of polypeptides modulate numerous aspects of development and are perceived at the cell surface by a complex of type I and type II TGF-β receptor serine/threonine kinases. TGF-β receptor interacting protein (TRIP-1) is a cytoplasmic substrate of the TGF-β type II receptor kinase and plays a role in TGF-β signaling. TRIP-1 is a WD domain protein that also functions as an essential subunit of the elF3 eukaryotic translation initiation factor in animals, yeast and plants. We previously cloned putative TRIP-1 homologs from bean and Arabidopsis and found that transgenic Arabidopsis plants expressing antisense TRIP-1 RNA exhibited a broad range of developmental defects including some morphological characteristics that resemble the phenotype of BR-deficient and - insensitive mutants. We now show that the BRI1 kinase domain phosphorylates Arabidopsis TRIP-1 on three specific sites in vitro (Thr-14, Thr-89 and either Thr-197 or Ser-198). Co-immunoprecipitation experiments using antibodies against TRIP-1, BRI1 and various fusion proteins strongly suggest that TRIP-1 and BRI1 also interact directly in vivo. These findings support a role for TRIP-1 in the molecular mechanisms of BR-regulated plant growth and development, possibly as a cytoplasmic substrate of the BRI1 receptor kinase.

Original languageEnglish (US)
Pages (from-to)251-261
Number of pages11
JournalPlant Journal
Volume43
Issue number2
DOIs
StatePublished - Jul 1 2005

Keywords

  • BAK1
  • BRI1
  • Brassinosteroids
  • Receptor kinase
  • TGF-β
  • TRIP-1

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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