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Cas1 and the Csy complex are opposing regulators of Cas2/3 nuclease activity
- Source :
- Proceedings of the National Academy of Sciences of the United States of America, vol 114, iss 26
- Publication Year :
- 2017
- Publisher :
- eScholarship, University of California, 2017.
-
Abstract
- The type I-F CRISPR adaptive immune system in Pseudomonas aeruginosa (PA14) consists of two CRISPR loci and six CRISPR-associated (cas) genes. Type I-F systems rely on a CRISPR RNA (crRNA)-guided surveillance complex (Csy complex) to bind foreign DNA and recruit a trans-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 (Cas2/32:Cas14) 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.
- Subjects :
- 0301 basic medicine
1.1 Normal biological development and functioning
Biology
03 medical and health sciences
chemistry.chemical_compound
Bacterial Proteins
Multienzyme Complexes
Cas1
Underpinning research
Genetics
CRISPR
Gene
Trans-activating crRNA
Nuclease
Multidisciplinary
Deoxyribonucleases
RNA
Cas
Acquired immune system
type I-F
Cell biology
030104 developmental biology
Emerging Infectious Diseases
PNAS Plus
chemistry
Pseudomonas aeruginosa
biology.protein
CRISPR Loci
CRISPR-Cas Systems
Cas2/3
DNA
Subjects
Details
- Database :
- OpenAIRE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America, vol 114, iss 26
- Accession number :
- edsair.doi.dedup.....00452d6190a3f1fea3ed89c6665b2953