Proteins that inhibit the activity of the CRISPR–Cas bacterial defence system could be widespread.
Viruses and other microbes often successfully transfer genes to bacteria, despite the presence of the bacterial CRISPR–Cas system, which recognizes and attacks foreign DNA or RNA. Karen Maxwell and Alan Davidson at the University of Toronto in Canada and their colleagues had previously described nine families of anti-CRISPR protein that help certain viruses to infect Pseudomonas bacteria. Now, using bioinformatics, the team has identified five more anti-CRISPR protein families in a range of microorganisms that inhibit CRISPR–Cas systems in Pseudomonas aeruginosa and Pectobacterium atrosepticum.
Anti-CRISPR proteins could have an important role in gene transfer between bacteria, including the spread of genes involved in antibiotic resistance, the authors say.
Nature Microbiol. http://dx.doi.org/10.1038/nmicrobiol.2016.85 (2016)