J. Biol. Chem., Vol. 283, Issue 12, 99909, March 21, 2008
Sharing Your Editor
Post-transcriptional cytosine-to-uracil editing is required for the proper processing of plant organellar RNA. Thus far, most information on plastid RNA editing has been obtained by analyzing chimeric transcripts in transplastomic tobacco chloroplasts in vivo, where results suggest that editing site clusters share trans-acting factors that catalyze the editing reaction.
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Sequence of maize RNA transcript rpoB highlighting the competitive trans-factor binding region upstream of the C467 editing site.
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In this Paper of the Week, Wade P. Heller and colleagues apply in vitro RNA editing in maize extracts to provide the first robust data for trans-factor sharing in a plant other than tobacco, demonstrating that transcripts encompassing two editing sites, ZMrpoB C467 and ZMrps14 C80, can compete for editing activity despite limited sequence similarity. The element they compete for is a single five-nucleotide sequence spanning the region from -20 to -16 relative to the edited C; this region also overlaps a 5' cis-element required for editing efficiency. These results indicate that the RNA sequences mediating both editing efficiency and cross-competition are highly similar and that a common trans-factor protein is involved in their editing. Such trans-factor sharing likely facilitates the editing of the large number of different C targets present in plant organelles (30-40 in chloroplasts and over 400 in mitochondria).
FOOTNOTES
See referenced article, J. Biol. Chem. 2008, 283, 7314-7319 

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Copyright © 2008 by the American Society for Biochemistry and Molecular Biology.