Sharrock, Bob , Clack, Ted , Liu, Peng .
Structure and activity of phytochrome heterodimers in Arabidopsis.
The Arabidopsis genome encodes five phytochrome apoproteins, which assemble with a bilin chromophore to produce red/far-red sensing photoreceptors. These phy holoproteins fall into two functionally distinct groups: type I phyA, which senses very low levels of light and continuous FR, and type II phyB-phyE, which sense long term R and the ratio of R:FR. We have used yeast two-hybrid analysis and co-immunoprecipitation experiments to investigate the binding interactions of these proteins. The phyA, phyB, and phyD C-terminal domains show positive yeast two hybrid interaction with themselves, as predicted for homodimerization, whereas the phyC and phyE C-termini do not. PhyB, phyD, and phyE also bind in heteromeric combinations with at least one other type II phytochrome in this assay. All five epitope-tagged apoproteins were constructed and shown to produce biologically active phytochromes in transgenic plants by complementation of mutant phenotypes and over-expression phenotypes. Co-immunoprecipitation assays utilizing the tagged phytochromes demonstrate that several heterodimeric combinations of the type II phyB-phyE proteins assemble in vivo. These results suggest that the repertoire of phytochrome forms in higher plants is more diverse than previously thought.
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1 - Montana State University, Department of Plant Sciences and Plant Pathology, 119 Plant Biology Building, Bozeman, MT, 59717-3150, USA
2 - Montana State University, Department of Plant Sciences and Plant Pathology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM