The intense selection pressure that CRISPR/Cas systems placed on viruses has resulted in the evolution of a number of anit-CRISPR proteins meant to silence this bacterial ‘immune system’.
Dong et al (2017) report on a database they constructed that aggregates current data on anti-CRISPR proteins.
Anti-CRISPR proteins were first discovered in 2013 and did not come as any surprise. Just as viral infections of eukaryotes have driven the evolution of anti-RNAi proteins, viral infections of bacteria have driven the evolution of anti-CRISPR proteins.
This video was produced to accompany Rauch et al (2017) which describes an anti-CRISPR system.
Dong et al. review briefly the types of anti-CRISPR proteins that have been found against both Class I and Class II CRISPR systems including commonly used SpCas9.
Anti-CRISPR proteins could be useful in developing strategies for controlling Cas9 activity both temporally and spatially. They could also be useful in limiting off-target effects.
Dong et al. manually gathered data on existing anti-CRISPR proteins and created “Anti-CRISPRdb”, a searchable, browse-able database containing protein and DNA sequences, source organisms, virulence, and various proteins that interact with the anti-CRISPR protein.
The Anti-CRISPRdb can be found at http://cefg.uestc.edu.cn/anit-CRISPRdb/
“The first version of anti-CRISPRdb currently contains 432 anti-CRISPR proteins and 106 non-redundant ones tested by experimental and bioinformatics methods. ” from anti-CRISPRdb
Given the popularity and power of SpCas9, the anti-CRISPR proteins descried for this system are likely to find their way into regular use. Those considering creative uses of CRISPR technologies will find this anti-CRISPRdb a potential source of ideas and reagents.
Chuan Dong, Ge-Fei Hao, Hong-Li Hua, Shuo Liu, Abraham Alemayehu Labena, Guoshi Chai, Jian Huang, Nini Rao, Feng-Biao Guo; Anti-CRISPRdb: a comprehensive online resource for anti-CRISPR proteins, Nucleic Acids Research, , gkx835, https://doi.org/10.1093/nar/gkx835