| Abstract Detail
Seed Biology Majee, Susmita Maitra [1], Chen, Tingsu [2], Martin, David [3], Downie, Bruce [3]. Reduced PIMT activity detrimentally influences seed vigor. L-aspartyl or L-asparaginyl residues are prone to spontaneous rearrangement into L-isoaspartyl (isoAsp) isomers, usually with deleterious consequences for the protein. L-isoAsp can be repaired to form L-Asp by the action of PROTEIN ISOASPARTYL METHYLTRANSFERASE (PIMT, EC 2.1.1.77) using S-adenosyl methionine as a methyl donor. We are interested in the consequences of isoAsp formation in orthodox seeds, which undergo maturation desiccation. These seeds are capable of surviving prolonged periods in a dehydrated state, conducive to isoAsp accumulation. Two genes encoding PIMT are present in Arabidopsis. On water, double mutant (pimt1-1, pimt2-1) seeds were found to have poor vigor relative to wild type (WT). Single mutant and WT seeds were no different in either the speed or completeness of germination on water but mutant seeds were more sensitive to 2µM cycloheximide than WT. Cycloheximide impairs de novo protein synthesis presumably leaving cells more reliant on protein repair than usual. There are either specific proteins, crucial for seed germination, that are particularly prone to isoAsp formation or there is a general decline in the integrity of the seed proteome. We are examining the double mutant seed proteome relative to that of the WT using on-blot methylation with the highly active human rPIMT to distinguish between these two eventualities. Regardless of this outcome, it is apparent that the repair mechanism embodied in PIMT is important for seed longevity in the dehydrated state.
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1 - University of Kentucky, Horticulture, 434 Plant Science Building, 1405 Veterans Drive, Lexington, Kentucky, 40546-0312, U.S.A.
2 - University of Goteborg, Cell and Molecular Biology, Box 462, 40530, Goteborg, Sweden
3 - University of Kentucky, Horticulture, 434 Plant Science Building, 1405 Veterans Drive, Lexington, KY, 40546
Keywords:
protein repair.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P29024
Abstract ID:1902 |
