Sequence-specific cleavage of dsRNA by Mini-III RNase
Glow, D., Pianka, D., Sulej, A.A., Kozlowski, L.P., Czarnecka, J., Chojnowski, G., Skowronek, K.J., Bujnicki, J.M.(2015) Nucleic Acids Res 43: 2864-2873
- PubMed: 25634891 
- DOI: https://doi.org/10.1093/nar/gkv009
- Primary Citation of Related Structures:  
4OUN - PubMed Abstract: 
Ribonucleases (RNases) play a critical role in RNA processing and degradation by hydrolyzing phosphodiester bonds (exo- or endonucleolytically). Many RNases that cut RNA internally exhibit substrate specificity, but their target sites are usually limited to one or a few specific nucleotides in single-stranded RNA and often in a context of a particular three-dimensional structure of the substrate. Thus far, no RNase counterparts of restriction enzymes have been identified which could cleave double-stranded RNA (dsRNA) in a sequence-specific manner. Here, we present evidence for a sequence-dependent cleavage of long dsRNA by RNase Mini-III from Bacillus subtilis (BsMiniIII). Analysis of the sites cleaved by this enzyme in limited digest of bacteriophage Φ6 dsRNA led to the identification of a consensus target sequence. We defined nucleotide residues within the preferred cleavage site that affected the efficiency of the cleavage and were essential for the discrimination of cleavable versus non-cleavable dsRNA sequences. We have also determined that the loop α5b-α6, a distinctive structural element in Mini-III RNases, is crucial for the specific cleavage, but not for dsRNA binding. Our results suggest that BsMiniIII may serve as a prototype of a sequence-specific dsRNase that could possibly be used for targeted cleavage of dsRNA.
Organizational Affiliation: 
Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology in Warsaw, ul. Ks. Trojdena 4, 02-109 Warsaw, Poland.