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RNA Repair System Discovered in Bacteria

In new papers appearing in Science and PNAS, University of Illinois biochemistry professor Dr. Raven H. Huang and colleagues describe the first RNA repair system to be discovered in bacteria. This is only the second RNA repair system discovered to date (with two proteins from T4 phage, a virus that attacks bacteria, as the first). The novelty of the newly discovered bacterial RNA repair system is that, before the damaged RNA is sealed, a methyl group is added to the two-prime hydroxyl group at the cleavage site of the damaged RNA, making it impossible to cleave the site again. Thus, the repaired RNA is "better than new." This discovery has implications for protecting cells against ribotoxins, a class of toxins that kills cells by cleaving essential RNAs involved in protein translation. Because the enzyme responsible for methylation in the newly-discovered RNA repair system is the Hen1 homolog in bacteria, the finding also has implications for the understanding of RNA interference and gene expression in plants, animals, and other eukaryotes. The eukaryotic Hen1 is one of three enzymes (along with Dicer and Argonaute) essential for the generation of small noncoding RNAs of 19-30 nucleotides in RNA interference. The new papers appear in the October 9 issue of Science and the October 12 online edition of PNAS. [Press release] [Science abstract] [PNAS abstract]