Phage AcrIIA2 DNA Mimicry: Structural Basis of the CRISPR and Anti-CRISPR Arms Race
Liang Liu, Maolu Yin, Min Wang, Yanli Wang
Summary
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 angstrom 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.
附件下载：
Phage AcrIIA2 DNA Mimicry: Structural Basis of the CRISPR and Anti-CRISPR Arms Race, MOL CELL, 31 Dec 2018
Molecular Cell, 31 December, 2018， DOI: https://doi.org/10.1016/j.molcel.2018.11.011
Phage AcrIIA2 DNA Mimicry: Structural Basis of the CRISPR and Anti-CRISPR Arms Race
Liang Liu, Maolu Yin, Min Wang, Yanli Wang
Summary
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 angstrom 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.
文章链接：https://www.cell.com/molecular-cell/fulltext/S1097-2765(18)30981-X#
相关报道：http://www.ibp.cas.cn/kyjz/zxdt/201901/t20190102_5224168.html