In prokaryotes, RNA derived from type I and type III CRISPR loci direct large ribonucleoprotein complexes to destroy invading bacteriophage and plasmids. In Escherichia coli, this 405-kDa complex is called Cascade. Here, we report the 3.03A crystal structure of Cascade bound to a single-stranded DNA target. The structure reveals that the CRISPR RNA and target strands do not form a double helix but instead adopt an underwound ribbon-like structure. This non-canonical structure is facilitated by rotation of every sixth nucleotide out of the RNA-DNA hybrid and is stabilized by the highly interlocked organization of protein subunits. These studies provide insight into both the assembly and the activity of this complex and suggest a mechanism to enforce fidelity of target binding.
Crystal structure of a CRISPR RNA-guided surveillance complex bound to a ssDNA target.,Mulepati S, Heroux A, Bailey S Science. 2014 Aug 14. pii: 1256996. PMID:25123481[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ Mulepati S, Heroux A, Bailey S. Crystal structure of a CRISPR RNA-guided surveillance complex bound to a ssDNA target. Science. 2014 Aug 14. pii: 1256996. PMID:25123481 doi:http://dx.doi.org/10.1126/science.1256996
