Suppression of cytochrome P450-mediated BR inactivation

Hao Peng, Michael M Neff

Overview

Brassinosteroids (BRs) are a group of steroid hormones regulating plant growth and development. BAS1 (CYP734A1, formerly CYP72B1) and SOB7 (CYP72C1) are two BR-inactivating cytochrome P450s identified in Arabidopsis thaliana. We previously found that a TF ATAF2 (ANAC081) suppresses BAS1 and SOB7 expression by binding to the Evening Element (EE) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1)-binding site (CBS) on their promoters. Both the EE and CBS are known binding targets of the circadian regulatory protein CCA1. Here, we confirm that as a transcriptional repressor, CCA1 binds the EE and CBS motifs on BAS1 and SOB7 promoters, respectively. CCA1 interacts with ATAF2 at both DNA–protein and protein–protein levels. ATAF2, BAS1, and SOB7 are all circadian regulated with distinct expression patterns.

Summary

CCA1 and ATAF2 differentially suppress BAS1- and SOB7-mediated BR inactivation.

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Author Comments

Dr. Hao Peng, PhD
Dr. Hao Peng, PhD
Washington State University
Research Scientist
Plant Biology, Crop Biotechnology
Pullman, Washington | United States
This research establishes the connection between circadian clock and BR homeostasis.Dr. Hao Peng, PhD

Resources

bioRxiv preprint
https://www.biorxiv.org/content/10.1101/457200v1

CIRCADIAN CLOCK ASSOCIATED 1 and ATAF2 differentially suppress cytochrome P450-mediated brassinosteroid inactivation.

Authors:
Dr. Hao Peng, PhD
Dr. Hao Peng, PhD
Washington State University
Research Scientist
Plant Biology, Crop Biotechnology
Pullman, Washington | United States

J Exp Bot 2020 Jan;71(3):970-985

Department of Crop and Soil Sciences, Washington State University, Pullman, WA, USA.

Brassinosteroids (BRs) are a group of steroid hormones regulating plant growth and development. Since BRs do not undergo transport among plant tissues, their metabolism is tightly regulated by transcription factors (TFs) and feedback loops. BAS1 (CYP734A1, formerly CYP72B1) and SOB7 (CYP72C1) are two BR-inactivating cytochrome P450s identified in Arabidopsis thaliana. We previously found that a TF ATAF2 (ANAC081) suppresses BAS1 and SOB7 expression by binding to the Evening Element (EE) and CIRCADIAN CLOCK ASSOCIATED 1 (CCA1)-binding site (CBS) on their promoters. Both the EE and CBS are known binding targets of the circadian regulatory protein CCA1. Here, we confirm that CCA1 binds the EE and CBS motifs on BAS1 and SOB7 promoters, respectively. Elevated accumulations of BAS1 and SOB7 transcripts in the CCA1 null mutant cca1-1 indicate that CCA1 is a repressor of their expression. When compared with either cca1-1 or the ATAF2 null mutant ataf2-2, the cca1-1 ataf2-2 double mutant shows higher SOB7 transcript accumulations and a stronger BR-insensitive phenotype of hypocotyl elongation in white light. CCA1 interacts with ATAF2 at both DNA-protein and protein-protein levels. ATAF2, BAS1, and SOB7 are all circadian regulated with distinct expression patterns. These results demonstrate that CCA1 and ATAF2 differentially suppress BAS1- and SOB7-mediated BR inactivation.

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Source
http://dx.doi.org/10.1093/jxb/erz468DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6977193PMC
January 2020
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(Supplied by CrossRef)
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SUPPRESSOR OF PHYTOCHROME B4-#3 represses genes associated with auxin signaling to modulate hypocotyl growth
Favero et al.
Plant Physiology 2016

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