Structural insights into the inactivation of the type I-F CRISPR-Cas system by anti-CRISPR proteins

ABSTRACT

Phage infection is one of the major threats to prokaryotic survival, and prokaryotes in turn have evolved multiple protection approaches to fight against this challenge. Various delicate mechanisms have been discovered from this eternal arms race, among which the CRISPR-Cas systems are the prokaryotic adaptive immune systems and phages evolve diverse anti-CRISPR (Acr) proteins to evade this immunity. Until now, about 90 families of Acr proteins have been identified, out of which 24 families were verified to fight against subtype I-F CRISPR-Cas systems. Here, we review the structural and biochemical mechanisms of the characterized type I-F Acr proteins, classify their inhibition mechanisms into two major groups and provide insights for future studies of other Acr proteins. Understanding Acr proteins in this context will lead to a variety of practical applications in genome editing and also provide exciting insights into the molecular arms race between prokaryotes and phages.

KEYWORDS:

• CRISPR-Cas systems
• anti-CRISPR
• type I-F system
• structure
• adaptive immune system

Acknowledgments

We thank the lab members from Yue Feng’s lab for their helpful comments. We apologize for those whose work were not cited in this study due to space limitation.

Authors’ contributions

L. Y. and P. Y. wrote the original manuscript. Y. F. and Y. Z. revised the manuscript. All the authors read and agreed on the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by funds from the National Natural Science Foundation of China [31822012 and 32000901], Beijing Natural Science Foundation (5204038), the National key research and development program of China [2017YFA0506500, 2019YFC1200500 and 2019YFC1200502], the Beijing Nova program, and the Fundamental Research Funds for the Central Universities [XK1802-8].