期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 109, 期 1, 页码 327-332出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1108321109
关键词
phosphotyrosine; signal transduction; phosphoserine; modification-specific antibodies
资金
- National Science Foundation [IOS-1022177, MCB-0740211, MCB-1021363]
- Department of Agriculture-Agricultural Research Service
- Direct For Biological Sciences
- Div Of Molecular and Cellular Bioscience [1021363] Funding Source: National Science Foundation
- Division Of Integrative Organismal Systems
- Direct For Biological Sciences [1022177] Funding Source: National Science Foundation
- Div Of Molecular and Cellular Bioscience
- Direct For Biological Sciences [0742411] Funding Source: National Science Foundation
The activity of the dual-specificity receptor kinase, brassinosteroid insensitive 1 (BRI1), reflects the balance between phosphorylation-dependent 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.
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