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ARS Home » Midwest Area » Urbana, Illinois » Global Change and Photosynthesis Research » Research » Publications at this Location » Publication #196565
Title: MOLECULAR MECHANISMS OF RECEPTOR KINASE ACTION IN BRASSINOSTEROID SIGNAL TRANSDUCTION

Author
item WANG, XIAOFENG - NC STATE UNIVERSITY
item GOSHE, MICHAEL - NC STATE UNIVERSITY
item KOTA, UMA - NC STATE UNIVERSITY
item HARDIN, SHANE - UNIVERSITY OF ILLINOIS
item Huber, Steven
item LI, JIA - UNIVERSITY OF OKLAHOMA
item CLOUSE, STEVEN - NC STATE UNIVERSITY

Submitted to: Iowa State University Biochemistry Biophysics and Molecular Biology Symposi
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2006
Publication Date: 7/10/2006
Citation: Wang, X., Goshe, M.B., Kota, U., Hardin, S., Huber, S.C., Li, J., Clouse, S.D. 2006. Molecular mechanisms of receptor kinase action in brassinosteroid signal transduction. Iowa State University Biochemistry Biophysics and Molecular Biology Symposium, July 10-14, 2006, Ames, Iowa. p. 32.

Interpretive Summary:

Technical Abstract: Brassinosteroids (BRs) regulate multiple aspects of plant growth and development and require an active BRASSINOSTEROID INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1) for hormone perception and signal transduction. To examine early events in BR signaling, we used co-immunoprecipitation of epitope-tagged proteins to show that in vivo association of BRI1 and BAK1 was affected by endogenous and exogenous BR levels and that phosphorylation of both BRI1 and BAK1 on Thr residues was BR-dependent. Immunoprecipitation of epitope-tagged BRI1 from Arabidopsis plants followed by liquid chromatography-tandem mass spectrometry (LC/MS/MS), identified multiple BRI1 in vivo phosphorylation sites. Site-directed mutagenesis of identified and predicted BRI1 phosphorylation sites revealed that two highly conserved activation loop residues were essential for kinase function in vitro and normal BRI1 signaling in planta. These results have been published (Wang et al., 2005, Plant Cell 17, 1685). Recently we have identified multiple in vivo sites of phosphorylation for BAK1 and have further examined the in vivo function of BRI1 by mutational analysis of specific phosphorylation sites. We are also using LC/MS/MS analysis of BRI1 and BAK1 immunoprecipitated from various genetic backgrounds to examine the detailed mechanisms of phosphorylation in response to BR. These studies should enhance our understanding of early events in BR signal transduction as well as general modes of action for plant receptor kinases.