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Abstract Detail


Organelle Biology

Reumann, Sigrun [1], Babujee, Lavanya [2], Ma, Changle [3], Wienkoop, Stephanie [4], Siemsen, Tanja [3], Antonicelli, Esteban [5], Rasche, Nicolas [3], Lueder, Franziska [6], Weckwerth, Wolfram [4], Jahn, Olaf [7].

Proteome Analysis of Arabidopsis Leaf Peroxisomes Reveals Novel Targeting Peptides and Compartmentalization of Unprecedented Metabolic Pathways and Defense Mechanisms.

In plants, the systematic analysis of peroxisomal proteins was so far hampered by the lack of highly enriched peroxisomes from model organisms such as Arabidopsis thaliana L. and an insufficient prediction accuracy of peroxisome-targeted proteins from genome sequences. We established an innovative protocol for the isolation of highly pure peroxisomes from mature Arabidopsis leaves and analyzed the proteome by complementary gel-based and gel-free approaches. Seventy-nine non-redundant proteins were identified, of which 43 proteins had previously not been associated with plant peroxisomes. Seventeen novel proteins carried predicted peroxisome targeting signals (PTS) type 1 or type 2 and eleven proteins PTS-related peptides not considered as functional PTS so far. Peroxisome targeting was confirmed for many novel proteins by in silico analyses and for eleven representative full-length fusion proteins by fluorescence microscopy. The targeting function of predicted and unpredicted signals was investigated and three tripeptides established as novel functional PTS1 peptides. In contrast to the generally accepted confinement of PTS2 peptides to the N-terminal domain, one peroxisomal matrix protein was demonstrated to carry a functional PTS2 at an internal position. Many novel enzymes have annotated functions related to beta-oxidation of complex compounds (e.g. polyunsaturated fatty acids, sterols, phenylacetate derivatives) or glutathione metabolism. The identification of seven proteins related to plant defense support the currently emerging evidence for an essential role of leaf peroxisomes in defense against pathogens and herbivores. In conclusion, our data provide new insights into the biology of plant peroxisomes and improve the prediction accuracy of peroxisome-targeted proteins from genome sequences.


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1 - Albrecht-von-Haller-Institute for Plant Sciences, Department of Plant Biochemistry, Justus-von-Liebig-Weg 11, Goettingen, D-37077, Germany
2 - Faculty of Agriculture, Department of Plant Pathology
3 - Albrecht-von-Haller-Institute for Plant Sciences, Department of Plant Biochemistry
4 - Max-Planck-Institute of Molecular Plant Physiology, Metabolic Networks
5 - Clemens Schöpf Institute, Biochemistry Department
6 - Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute
7 - Max-Planck-Institute of Experimental Medicine, Proteomics Group

Keywords:
peroxisomes
beta-oxidation
photorespiration
defense
detoxification
proteomics
targeting prediction.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P18010
Abstract ID:300


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