Chloroplast RNase J compensates for inefficient transcription termination by removal of antisense RNA
- 1Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA
- 2Department of Biology, Technion–Israel Institute of Technology, Haifa 32000, Israel
Abstract
Ribonuclease J is an essential enzyme, and the Bacillus subtilis ortholog possesses both endoribonuclease and 5′ → 3′ exoribonuclease activities. Chloroplasts also contain RNase J, which has been postulated to participate, as both an exo- and endonuclease, in the maturation of polycistronic mRNAs. Here we have examined recombinant Arabidopsis RNase J and found both 5′ → 3′ exoribonuclease and endonucleolytic activities. Virus-induced gene silencing was used to reduce RNase J expression in Arabidopsis and Nicotiana benthamiana, leading to chlorosis but surprisingly few disruptions in the cleavage of polycistronic rRNA and mRNA precursors. In contrast, antisense RNAs accumulated massively, suggesting that the failure of chloroplast RNA polymerase to terminate effectively leads to extensive symmetric transcription products that are normally eliminated by RNase J. Mung bean nuclease digestion and polysome analysis revealed that this antisense RNA forms duplexes with sense strand transcripts and prevents their translation. We conclude that a major role of chloroplast RNase J is RNA surveillance to prevent overaccumulation of antisense RNA, which would otherwise exert deleterious effects on chloroplast gene expression.
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Footnotes
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↵4 Corresponding author.
E-mail ds28{at}cornell.edu.
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Article published online ahead of print. Article and publication date are at http://www.rnajournal.org/cgi/doi/10.1261/rna.028043.111.
- Received May 4, 2011.
- Accepted September 13, 2011.
- Copyright © 2011 RNA Society