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-Structure paper
Title | Cas1 and the Csy complex are opposing regulators of Cas2/3 nuclease activity. |
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Journal, issue, pages | Proc Natl Acad Sci U S A, Vol. 114, Issue 26, Page E5113-E5121, Year 2017 |
Publish date | Jun 27, 2017 |
Authors | MaryClare F Rollins / Saikat Chowdhury / Joshua Carter / Sarah M Golden / Royce A Wilkinson / Joseph Bondy-Denomy / Gabriel C Lander / Blake Wiedenheft / |
PubMed Abstract | The type I-F CRISPR adaptive immune system in (PA14) consists of two CRISPR loci and six CRISPR-associated () genes. Type I-F systems rely on a CRISPR RNA (crRNA)-guided surveillance complex (Csy ...The type I-F CRISPR adaptive immune system in (PA14) consists of two CRISPR loci and six CRISPR-associated () genes. Type I-F systems rely on a CRISPR RNA (crRNA)-guided surveillance complex (Csy complex) to bind foreign DNA and recruit a -acting nuclease (i.e., Cas2/3) for target degradation. In most type I systems, Cas2 and Cas3 are separate proteins involved in adaptation and interference, respectively. However, in I-F systems, these proteins are fused into a single polypeptide. Here we use biochemical and structural methods to show that two molecules of Cas2/3 assemble with four molecules of Cas1 (Cas2/3:Cas1) into a four-lobed propeller-shaped structure, where the two Cas2 domains form a central hub (twofold axis of symmetry) flanked by two Cas1 lobes and two Cas3 lobes. We show that the Cas1 subunits repress Cas2/3 nuclease activity and that foreign DNA recognition by the Csy complex activates Cas2/3, resulting in bidirectional degradation of DNA targets. Collectively, this work provides a structure of the Cas1-2/3 complex and explains how Cas1 and the target-bound Csy complex play opposing roles in the regulation of Cas2/3 nuclease activity. |
External links | Proc Natl Acad Sci U S A / PubMed:28438998 / PubMed Central |
Methods | EM (single particle) |
Resolution | 15.6 Å |
Structure data | EMDB-8558: |
Source |
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