Belanger, Eileen , Flores, Daisy , Kimoto, Maryann , Belletto, John , Hoiness, Robert , Alvaro, Bethel , Brusslan, Judy .
A Bioinformatics Approach for the Identification of Chloroplast Proteases that Play a Role in Senescence.
Senescence is the final developmental stage in leaves. Nitrogen and other cellular components are transported out of the senescing cell and into growing tissues. Senescence begins in intact chloroplasts with reductions in photosynthesis and Rubisco protein levels, however the proteases responsible for this process have not yet been defined (Hortensteiner and Feller, 2001). With this in mind we set out to identify proteases which could be involved in chloroplast senescence using a bioinformatics approach.
We began our search using the MEROPS database and TargetP. MEROPS is a protease database which identifies and organizes proteases for organisms throughout the kingdom of life. MEROPS lists 674 proteases and 148 non-peptidase homologues for Arabidopsis. TargetP compares the N-terminal amino acid region to a database of known target sequences in order to predict cellular localization. By analyzing the location of all MEROPS-identified Arabidopsis proteases in TargetP, 115 proteases were identified that were likely to be chloroplast localized (C4 or above).
We next turned to Genevestigator, a database containing microarray information for both Arabidopsis and mouse. Using data from experiments 88.19-88.27 (control leaves) and 88.52-88.54 (senescent leaves), 17 chloroplast proteases were identified that showed a two fold or greater induction during senescence.
To determine whether these proteases are indeed involved in chloroplast senescence, we are using a three pronged experimental approach. Real time QPCR will be used to confirm that these protease genes are being upregulated in senescence, GFP constructs will be made to confirm chloroplast localization, and knockout lines will be assessed for senescence-associated phenotypes.
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1 - California State University, Long Beach, Biological Sciences, 1250 Bellflower Blvd., Long Beach, CA, 90840-3702, USA
2 - California State University, Long Beach, Biological Sciences
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM