| Abstract Detail
Secondary Metabolism Winkel, Brenda S. J. [1], Ramirez, Melissa [2]. Interaction-dependent localization of flavonoid enzymes in Arabidopsis. Flavonoid biosynthesis is a well-characterized specialized metabolic pathway found exclusively in plants. The diverse end-products have a variety of key physiological functions in plants and convey important health benefits and medicinal properties to plants consumed by humans. Until recently, it was believed that flavonoid biosynthesis occurred exclusively in the cytoplasm and that the products were then transported to sites of action within the cell. However, new evidence indicates the presence of at least two flavonoid enzymes, chalcone synthase (CHS) and chalcone isomerase (CHI), in the nucleus, suggesting that the synthesis of nuclear flavonoids may occur in situ. CHS contains a sequence similar to a classic nuclear localization signal (NLS), while CHI does not. Interestingly, the putative NLS is located at the predicted interaction interface of these two enzymes. Current studies explore the possibility that subcellular localization of flavonoid enzymes is affected by or dependent upon specific protein-protein interactions. This work also addresses the possibility that enzyme localization determines the types and cellular locations of end products that are produced in response to diverse biotic and environmental cues. Confocal laser scanning microscopy is being used to examine the localization of these enzymes expressed from their native promoters as a fusion to green fluorescent protein in stably-transformed plants. This approach is also being used to determine the role of the putative NLS of CHS in the localization of CHS or of the CHS:CHI bienzyme complex using site-directed mutagenesis. This work represents an essential step toward elucidating the mechanisms that organize related metabolic enzymes within the crowded environment of the cell interior.
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1 - Virginia Tech, Department of Biological Sciences, 409 Latham Hall, Ag-Quad Lane, Blacksburg, VA, 24061, USA
2 - Virginia Tech, Department of Biological Sciences, 432 Latham Hall, Ag-Quad Lane, Blacksburg, VA, 24061, USA
Keywords:
flavonoid biosynthesis
chalcone synthase
multienzyme complexes
nuclear localization.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P20019
Abstract ID:337 |
