7SBA

Structure of type I-D Cascade bound to a dsDNA target

Summary for 7SBA

• Entry DOI: 10.2210/pdb7sba/pdb
• EMDB information: 24974
• Descriptor: Cas7d, Cas5d, Cas10d, ... (7 entities in total)
• Functional Keywords: crispr, complex, ribonucleoprotein complex, type i-d, type id, type i, cyanobacteria, synechocystis, rna binding protein, dna binding protein, dna binding protein-dna-rna complex, dna binding protein/dna/rna
• Biological source: Synechocystis sp. PCC 6803; More
• Total number of polymer chains: 14
• Total formula weight: 453279.89

Authors

Schwartz, E.A.,Taylor, D.W. (deposition date: 2021-09-24, release date: 2022-06-08, Last modification date: 2024-06-05)

Primary citation

Schwartz, E.A.,McBride, T.M.,Bravo, J.P.K.,Wrapp, D.,Fineran, P.C.,Fagerlund, R.D.,Taylor, D.W.
Structural rearrangements allow nucleic acid discrimination by type I-D Cascade.
Nat Commun, 13:2829-2829, 2022

PubMed Abstract: CRISPR-Cas systems are adaptive immune systems that protect prokaryotes from foreign nucleic acids, such as bacteriophages. Two of the most prevalent CRISPR-Cas systems include type I and type III. Interestingly, the type I-D interference proteins contain characteristic features of both type I and type III systems. Here, we present the structures of type I-D Cascade bound to both a double-stranded (ds)DNA and a single-stranded (ss)RNA target at 2.9 and 3.1 Å, respectively. We show that type I-D Cascade is capable of specifically binding ssRNA and reveal how PAM recognition of dsDNA targets initiates long-range structural rearrangements that likely primes Cas10d for Cas3' binding and subsequent non-target strand DNA cleavage. These structures allow us to model how binding of the anti-CRISPR protein AcrID1 likely blocks target dsDNA binding via competitive inhibition of the DNA substrate engagement with the Cas10d active site. This work elucidates the unique mechanisms used by type I-D Cascade for discrimination of single-stranded and double stranded targets. Thus, our data supports a model for the hybrid nature of this complex with features of type III and type I systems.

PubMed: 35595728
DOI: 10.1038/s41467-022-30402-8

Experimental method

ELECTRON MICROSCOPY (2.9 Å)