6IFO

Crystal structure of AcrIIA2-SpyCas9-sgRNA ternary complex

Summary for 6IFO

• Entry DOI: 10.2210/pdb6ifo/pdb
• Descriptor: CRISPR-associated endonuclease Cas9/Csn1, RNA (99-MER), AcrIIA2 (3 entities in total)
• Functional Keywords: anti-crispr, spycas9, sgrna, acriia2, rna binding protein-rna complex, rna binding protein/rna
• Biological source: Streptococcus pyogenes serotype M1; More
• Total number of polymer chains: 6
• Total formula weight: 409899.00

Authors

Liu, L.,Wang, Y. (deposition date: 2018-09-20, release date: 2019-01-23, Last modification date: 2023-11-22)

Primary citation

Liu, L.,Yin, M.,Wang, M.,Wang, Y.
Phage AcrIIA2 DNA Mimicry: Structural Basis of the CRISPR and Anti-CRISPR Arms Race.
Mol. Cell, 73:611-620.e3, 2019

PubMed Abstract: CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated proteins) systems provide prokaryotic cells with adaptive immunity against invading bacteriophages. Bacteriophages counteract bacterial responses by encoding anti-CRISPR inhibitor proteins (Acr). However, the structural basis for their inhibitory actions remains largely unknown. Here, we report the crystal structure of the AcrIIA2-SpyCas9-sgRNA (single-guide RNA) complex at 3.3 Å resolution. We show that AcrIIA2 binds SpyCas9 at a position similar to the target DNA binding region. More specifically, AcrIIA2 interacts with the protospacer adjacent motif (PAM) recognition residues of Cas9, preventing target double-stranded DNA (dsDNA) detection. Thus, phage-encoded AcrIIA2 appears to act as a DNA mimic that blocks subsequent dsDNA binding by virtue of its highly acidic residues, disabling bacterial Cas9 by competing with target dsDNA binding with a binding motif distinct from AcrIIA4. Our study provides a more detailed mechanistic understanding of AcrIIA2-mediated inhibition of SpyCas9, the most widely used genome-editing tool, opening new avenues for improved regulatory precision during genome editing.

PubMed: 30606466
DOI: 10.1016/j.molcel.2018.11.011

Experimental method

X-RAY DIFFRACTION (3.313 Å)