| Abstract Detail
Mechanisms of Gene Regulation Madzima, Thelma [1], Kaufman, Lon [2], Folta, Kevin M. [3]. KFR1, A novel Kelch-domain, F-box protein regulates ubiquitination-dependent transcript stability. RNA degradation regulates accumulation of Light-harvesting, chlorophyll-binding (Lhcb; formerly cab) transcripts. In the etiolated seedling, Lhcb transcript levels increase in response to a short, single low fluence pulse of blue light (104 µmol m-2), yet they are destabilized by a single pulse of blue-high-fluence light (BHF; 105 µmol m-2). The 65 b 5’-UTR is necessary and sufficient to confer BHF-mediated destabilization. To identify potential regulatory proteins, a yeast-three-hybrid screen was performed using the Lhcb 5’-UTR as an interaction target. Several bona fide interactors were obtained. One protein shown to associate with the transcript in yeast is a novel protein designated as KFR1 for Kelch domain, F-box RNA-associated protein. Genetic tests in Arabidopsis T-DNA insertion mutants indicate that Kfr1 is required for BHF-induced Lhcb transcript destabilization. Since KFR1 does not possess described RNA-binding domains, we hypothesized that the F-box entity may be binding to a separate protein that stabilizes the transcript, and subsequently targets it for degradation in response to environmental cues. This hypothesis was tested by application of MG-132 (a proteosome inhibitor) prior to light treatment. The BLF response was not affected, but the inhibitor blocked the BHF response, leading to abnormal accumulation of Lhcb transcripts. No other photomorphogenic defects were observed in kfr1 mutants. Taken together, the results indicate that KFR1 is active in ubiquitination-dependent, light-mediated RNA metabolism and not in light signaling directly. We are now exploring the precise mechanism of KFR1’s role in the regulation of transcript stability, as well as the scope of its influence on other transcripts.
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http://www.arabidopsisthaliana.com
1 - University of Florida, Graduate Program in Plant Molecular and Cellular Biology, P.O. Box 110690, Gainesville, FL, 32611, USA
2 - University of Illinois at Chicago, Department of Biological Sciences
3 - University of Florida, Horticultural Sciences Department
Keywords:
Transcript stability
blue light
F-Box protein
ubiquitination.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P36012
Abstract ID:512 |
