| Abstract Detail
Protein Modification and Turnover Farrokhi, Naser [1], Whitelegge, Julian [2], Brusslan, Judy [3]. Comparative nanopeptidomics of Arabidopsis chloroplasts: An approach towards identification of in vivo substrates of an acylaminoacyl-peptidase. Proteolytic enzymes, both proteases and peptidases, are involved in many aspects of cell physiology such as breakdown of storage proteins during seed germination, protein remobilization upon senescence, removal of transit peptides during protein import to organelles, and recycling of damaged or misfolded proteins. These enzymes process their specific endogenous substrate(s) leading to short peptides or amino acids, which can have important roles in other cellular processes such as signaling, defense and biogenesis. Although in Arabidopsis more than 650 protease have been predicted to be involved in different steps of protein hydrolysis in different parts of the cell, true cellular substrates have been demonstrated for only a few of these enzymes.
In our laboratory we functionally characterized a chloroplast-localized acylaminoacyl-peptidase (cAAP; At5g36210), which catalyzes the removal of a N α-acetylated amino acid from short peptides enhancing plant survival under etiolated conditions. In order to ascertain the in vivo substrate(s) of cAAP, a comparative peptidomics approach was undertaken to identify the N-terminally modified short peptides that were degraded in the wild-type peptide pool but present in the caap peptide pool. Stromal peptides extracted from intact chloroplasts of both wild-type plants and caap mutants were fractionated via liquid chromatography and unique peaks were apparent in caap. The peptides in these peaks were further separated on a NanoLC and sequenced via tandem mass spectrometry. Our findings indicate that alanine and proline were the most common acetylated residues of peptides that accumulated in caap.
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1 - California State University, Long Beach, Biological Sciences
2 - UCLA, Pasarow Mass Spectrometry Facility
3 - California State University, Long Beach, Biological Sciences, 1250 Bellflower Blvd., Long Beach, CA, 90840-3702, USA
Keywords:
peptidomics
chloroplast protease.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P37005
Abstract ID:272 |
