7FIA

Structure of AcrIF23

Summary for 7FIA

• Entry DOI: 10.2210/pdb7fia/pdb
• Descriptor: AcrIF23 (2 entities in total)
• Functional Keywords: inhibitor, viral protein
• Biological source: Pseudomonas aeruginosa
• Total number of polymer chains: 1
• Total formula weight: 17716.77

Authors

Ren, J.,Yue, F. (deposition date: 2021-07-30, release date: 2022-07-27, Last modification date: 2024-05-29)

Primary citation

Ren, J.,Wang, H.,Yang, L.,Li, F.,Wu, Y.,Luo, Z.,Chen, Z.,Zhang, Y.,Feng, Y.
Structural and mechanistic insights into the inhibition of type I-F CRISPR-Cas system by anti-CRISPR protein AcrIF23.
J.Biol.Chem., 298:102124-102124, 2022

PubMed Abstract: Prokaryotes evolved clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins as a kind of adaptive immune defense against mobile genetic elements including harmful phages. To counteract this defense, many mobile genetic elements in turn encode anti-CRISPR proteins (Acrs) to inactivate the CRISPR-Cas system. While multiple mechanisms of Acrs have been uncovered, it remains unknown whether other mechanisms are utilized by uncharacterized Acrs. Here, we report a novel mechanism adopted by recently identified AcrIF23. We show that AcrIF23 interacts with the Cas2/3 helicase-nuclease in the type I-F CRISPR-Cas system, similar to AcrIF3. The structure of AcrIF23 demonstrated a novel fold and structure-based mutagenesis identified a surface region of AcrIF23 involved in both Cas2/3-binding and its inhibition capacity. Unlike AcrIF3, however, we found AcrIF23 only potently inhibits the DNA cleavage activity of Cas2/3 but does not hinder the recruitment of Cas2/3 to the CRISPR RNA-guided surveillance complex (the Csy complex). Also, in contrast to AcrIF3 which hinders substrate DNA recognition by Cas2/3, we show AcrIF23 promotes DNA binding to Cas2/3. Taken together, our study identifies a novel anti-CRISPR mechanism used by AcrIF23 and highlights the diverse mechanisms adopted by Acrs.

PubMed: 35697070
DOI: 10.1016/j.jbc.2022.102124

Experimental method

X-RAY DIFFRACTION (2.13 Å)