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Structural biology. Crystal structure of a CRISPR RNA-guided surveillance complex bound to a ssDNA target.

ABSTRACT: 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-kilodalton complex is called Cascade. We report the crystal structure of Cascade bound to a single-stranded DNA (ssDNA) target at a resolution of 3.03 angstroms. 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 noncanonical 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.

SUBMITTER: Mulepati S

PROVIDER: S-EPMC4427192 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Structural biology. Crystal structure of a CRISPR RNA-guided surveillance complex bound to a ssDNA target.

Mulepati Sabin S Héroux Annie A Bailey Scott S

Science (New York, N.Y.) 20140814 6203

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-kilodalton complex is called Cascade. We report the crystal structure of Cascade bound to a single-stranded DNA (ssDNA) target at a resolution of 3.03 angstroms. 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 noncan ...[more]

PMID: 25123481

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