We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
A stepwise model for double-stranded RNA processing by ribonuclease III.
- Authors
Jianhua Gan; Shaw, Gary; Tropea, Joseph E.; Waugh, David S.; Court, Donald L.; Xinhua Ji
- Abstract
RNA interference is mediated by small interfering RNAs produced by members of the ribonuclease III (RNase III) family represented by bacterial RNase III and eukaryotic Rnt1p, Drosha and Dicer. For mechanistic studies, bacterial RNase III has been a valuable model system for the family. Previously, we have shown that RNase III uses two catalytic sites to create the 2-nucleotide (nt) 3′ overhangs in its products. Here, we present three crystal structures of RNase III in complex with double-stranded RNA, demonstrating how Mg2+ is essential for the formation of a catalytically competent protein–RNA complex, how the use of two Mg2+ ions can drive the hydrolysis of each phosphodiester bond, and how conformational changes in both the substrate and the protein are critical elements for assembling the catalytic complex. Moreover, we have modelled a protein–substrate complex and a protein–reaction intermediate (transition state) complex on the basis of the crystal structures. Together, the crystal structures and the models suggest a stepwise mechanism for RNase III to execute the phosphoryl transfer reaction.
- Subjects
RNA; HYDROLYSIS; NUCLEIC acids; RIBOSE; SOLVOLYSIS; RIBONUCLEASES
- Publication
Molecular Microbiology, 2008, Vol 67, Issue 1, p143
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/j.1365-2958.2007.06032.x