| Popup Text: | ABSTRACT
"Control of Brassinosteroid Genomic Responses : When phosphorylation takes the lead"
Plant growth is shaped by the dynamic integration of environmental, developmental, and metabolic cues. Information from many of these input pathways feeds into the highly connected network of small molecule phytohormones. Our studies focus on the downstream events in the brassinosteroid signaling pathway, and characterized the role of kelch-repeat containing proteins and GSK3 kinases. Our work demonstrated that the BR-regulated GSK3 kinase BIN2 and the kelch-repeat phosphatase BSU1 control in the nucleus both the binding to target promoters and the transcriptional activity of the transcription factor BES1, via phosphorylation. We are also investigating the mechanism by which auxin and brassinosteroid signals together modulate gene expression and growth. Looking for BIN2 interacting proteins, we unco
vered a molecular connection between brassinosteroid and auxin signaling pathways. The BIN2 kinase interacts with and phosphorylates the repressor Auxin Response Factor ARF2 to modify its binding to DNA and repressor activity. Together, these data suggest a model where BIN2 increases expression of auxin-induced genes by directly inactivating repressor ARFs, leading to synergistic increases in transcription.
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