| Abstract Detail
Metabolism Ikegami, Ayako [1], Inoue, Kentaro [2]. Suborganellar localization of carotenogenic enzymes. Carotenoids play important roles in both photosynthetic and non-photosynthetic tissues. Most enzymes responsible for their biosynthesis have been identified from a wide variety of plants at molecular level. Furthermore, the importance of transcriptional regulation in carotenoid biosynthesis has been well established. Several carotenogenic enzymes are predicted to be associated with internal membranes in plastids. In contrast to the gene expression patterns, however, localization of these enzymes has not been fully explored yet. We hypothesize that assembly of proteins in a certain suborganellar compartment in addition to accumulation of transcripts plays key regulatory roles in carotenoid biosynthesis. As a first step to test this, we examined properties of five proteins from citrus, phytoene synthase (CitPsy), phyotene desaturase (CitPds), lycopene-β-cyclase (CitLcyb), lycopene-ε-cyclase (CitLcye), and carotene β-ring hydroxylase (CitChyb), and lycopene cyclases from Arabidopsis (AtLcyb and AtLcye). By bacterial color complementation assay, we verified their catalytic activities. By import assay using isolated chloroplasts, we confirmed that CitPsy was peripherally associated with the membrane, while CitPds was mainly located in the stroma. All lycopene cyclases were targeted to both the soluble and membrane compartments, although Lcyes showed a stronger association to the membrane compared to Lcybs. Finally, CitChyb was exclusively inserted into the chloroplast internal membrane. We have been developing additional biochemical and genetic tools to elucidate the regulation of suborganellar localization of these carotenogenic enzymes.
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Related Links:
Inoue lab in UC Davis
1 - University of California at Davis, Plant Sciences, One Shields Avenue, Davis, CA, 95616, USA
2 - University of California at Davis, Plant Sciences, CAES, One Shields Avenue, Davis, CA, 95616, USA
Keywords:
carotenoid
Citrus
membrane
protein import
Plastid.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P19041
Abstract ID:2298 |
