A Type I-F Anti-CRISPR Protein Inhibits the CRISPR-Cas Surveillance Complex by ADP-Ribosylation.
Niu, Y., Yang, L., Gao, T., Dong, C., Zhang, B., Yin, P., Hopp, A.K., Li, D., Gan, R., Wang, H., Liu, X., Cao, X., Xie, Y., Meng, X., Deng, H., Zhang, X., Ren, J., Hottiger, M.O., Chen, Z., Zhang, Y., Liu, X., Feng, Y.(2020) Mol Cell 80: 512-524.e5
- PubMed: 33049228 
- DOI: https://doi.org/10.1016/j.molcel.2020.09.015
- Primary Citation of Related Structures:  
6KYF - PubMed Abstract: 
CRISPR-Cas systems are bacterial anti-viral systems, and phages use anti-CRISPR proteins (Acrs) to inactivate these systems. Here, we report a novel mechanism by which AcrIF11 inhibits the type I-F CRISPR system. Our structural and biochemical studies demonstrate that AcrIF11 functions as a novel mono-ADP-ribosyltransferase (mART) to modify N250 of the Cas8f subunit, a residue required for recognition of the protospacer-adjacent motif, within the crRNA-guided surveillance (Csy) complex from Pseudomonas aeruginosa. The AcrIF11-mediated ADP-ribosylation of the Csy complex results in complete loss of its double-stranded DNA (dsDNA) binding activity. Biochemical studies show that AcrIF11 requires, besides Cas8f, the Cas7.6f subunit for binding to and modifying the Csy complex. Our study not only reveals an unprecedented mechanism of type I CRISPR-Cas inhibition and the evolutionary arms race between phages and bacteria but also suggests an approach for designing highly potent regulatory tools in the future applications of type I CRISPR-Cas systems.
Organizational Affiliation: 
Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing Key Laboratory of Bioprocess, State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China.