Journal article
Arabidopsis CYP72C1 is an atypical cytochrome P450 that inactivates brassinosteroids
Plant molecular biology, Vol.74(1), pp.167-181
09/2010
Handle:
https://hdl.handle.net/2376/110193
PMID: 20669042
Abstract
Cytochrome P450 monooxygenases (P450s) are a diverse family of proteins that have specialized roles in secondary metabolism and in normal cell development. Two P450s in particular, CYP734A1 and CYP72C1, have been identified as brassinosteroid-inactivating enzymes important for steroid-mediated signal transduction in Arabidopsis thaliana. Genetic analyses have demonstrated that these P450s modulate growth throughout plant development. While members of the CYP734A subfamily inactivate brassinosteroids through C-26 hydroxylation, the biochemical activity of CYP72C1 is unknown. Because CYP734A1 and CYP72C1 in Arabidopsis diverge more than brassinosteroid inactivating P450s in other plants, this study examines the structure and biochemistry of each enzyme. Three-dimensional models were generated to examine the substrate binding site structures and determine how they might affect the function of each P450. These models have indicated that the active site of CYP72C1 does not contain several conserved amino acids typically needed for substrate hydroxylation. Heterologous expression of these P450s followed by substrate binding analyses have indicated that CYP734A1 binds active brassinosteroids, brassinolide and castasterone, as well as their upstream precursors whereas CYP72C1 binds precursors more effectively. Seedling growth assays have demonstrated that the genetic state of CYP734A1, but not CYP72C1, affected responsiveness to high levels of exogenous brassinolide supporting our observations that CYP72C1 acts on brassinolide precursors. Although there may be some overlap in their physiological function, the distinct biochemical functions of these proteins in Arabidopsis has significant potential to fine-tune the levels of different brassinosteroid hormones throughout plant growth and development.
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Details
- Title
- Arabidopsis CYP72C1 is an atypical cytochrome P450 that inactivates brassinosteroids
- Creators
- Leeann Thornton - Department of Biology The College of New Jersey 2000 Pennington Rd. Ewing NJ 08628 USASanjeewa Rupasinghe - Department of Cell and Developmental Biology University of Illinois Urbana IL 61801 USAHao Peng - Department of Crop and Soil Sciences Washington State University Pullman WA 99164 USAMary Schuler - Department of Cell and Developmental Biology University of Illinois Urbana IL 61801 USAMichael Neff - Department of Crop and Soil Sciences Washington State University Pullman WA 99164 USA
- Publication Details
- Plant molecular biology, Vol.74(1), pp.167-181
- Academic Unit
- Crop and Soil Sciences, Department of
- Publisher
- Springer Netherlands; Dordrecht
- Identifiers
- 99900547364901842
- Language
- English
- Resource Type
- Journal article