7JTA

Crystal structure of a putative nuclease with anti-Cas9 activity from an uncultured Clostridia bacterium

7JTA の概要

• エントリーDOI: 10.2210/pdb7jta/pdb
• 分子名称: NTF2-like nuclease/anti-CRISPR, NITRATE ION, (4S)-2-METHYL-2,4-PENTANEDIOL, ... (4 entities in total)
• 機能のキーワード: anti-crispr, nuclease, phage protein, cas9, unknown function
• 由来する生物種: Clostridia bacterium
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 13340.87

構造登録者

Werther, R.,Forsberg, K.J.,Stoddard, B.L. (登録日: 2020-08-17, 公開日: 2021-09-22, 最終更新日: 2024-10-30)

主引用文献

Forsberg, K.J.,Schmidtke, D.T.,Werther, R.,Uribe, R.V.,Hausman, D.,Sommer, M.O.A.,Stoddard, B.L.,Kaiser, B.K.,Malik, H.S.
The novel anti-CRISPR AcrIIA22 relieves DNA torsion in target plasmids and impairs SpyCas9 activity.
Plos Biol., 19:e3001428-e3001428, 2021

PubMed Abstract: To overcome CRISPR-Cas defense systems, many phages and mobile genetic elements (MGEs) encode CRISPR-Cas inhibitors called anti-CRISPRs (Acrs). Nearly all characterized Acrs directly bind Cas proteins to inactivate CRISPR immunity. Here, using functional metagenomic selection, we describe AcrIIA22, an unconventional Acr found in hypervariable genomic regions of clostridial bacteria and their prophages from human gut microbiomes. AcrIIA22 does not bind strongly to SpyCas9 but nonetheless potently inhibits its activity against plasmids. To gain insight into its mechanism, we obtained an X-ray crystal structure of AcrIIA22, which revealed homology to PC4-like nucleic acid-binding proteins. Based on mutational analyses and functional assays, we deduced that acrIIA22 encodes a DNA nickase that relieves torsional stress in supercoiled plasmids. This may render them less susceptible to SpyCas9, which uses free energy from negative supercoils to form stable R-loops. Modifying DNA topology may provide an additional route to CRISPR-Cas resistance in phages and MGEs.

PubMed: 34644300
DOI: 10.1371/journal.pbio.3001428

実験手法

X-RAY DIFFRACTION (2.801 Å)