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Abstract Detail


Organelle Biology

Germain, Arnaud [1], Stern, David [2].

Exploration of the diverse roles of PNPase using the TILLING approach.

Chloroplast genes and metabolic activities are regulated by the products of nuclear genes, acting mostly at the post-transcriptional level. One of the numerous ways to regulate the expression of chloroplast genes is by modulating RNA stability through sequential degradation events. This degradation begins with endonucleolytic cleavage and is followed by the addition of a poly(A)-rich tail and exonucleolytic degradation of polyadenylated cleavage products by 3’ to 5’ exoribonucleases. Polynucleotide phosphorylase (PNPase) is one of two exoribonucleases involved in chloroplast RNA turnover, and catalyzes both the processive 3’ to 5’ phosphorolysis of chloroplast RNA and its processive polymerization, depending on the ratio between inorganic phosphate and nucleoside diphosphates. The molecular and phenotypic characterization of Arabidopis thaliana PNPase null mutants showed a chlorotic phenotype in young leaves that became less severe as leaves matured, and showed dramatic changes in the processing and accumulation of several chloroplast-encoded RNAs. To further investigate how PNPase deficiency results in such a major defect in chloroplast RNA metabolism, we obtained TILLING mutants to test the effects of single amino acid substitutions in its two core catalytic domains. We will report that the observations made on the null mutants can be dissected in some TILLING lines, suggesting that the two core domains of PNPase play different roles at various steps of the chloroplast RNA metabolism.


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Related Links:
http://bti.cornell.edu/page.php?id=335


1 - Boyce Thompson Institute for Plant Research, Tower Rd, Ithaca, NY, 14853, USA
2 - Boyce Thompson Institute for Plant Research

Keywords:
Chloroplast
RNA processing
TILLING.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P18023
Abstract ID:1343


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