Cooperation between CRISPR-Cas types enables adaptation in an RNA-targeting system [article]

Ville Hoikkala, Janne J Ravantti, Cesar Diez-Villasenor, Marja Tiirola, Rachel Conrad, Mark J McBride, Lotta-Riina Sundberg
2020 bioRxiv   pre-print
CRISPR-Cas immune systems adapt to new threats by acquiring spacers from invading nucleic acids such as phage genomes. However, some CRISPR-Cas loci lack genes necessary for spacer acquisition, despite apparent variation in spacer content between strains. It has been suggested that such loci may use acquisition machinery from co-occurring CRISPR-Cas systems. Here, using a lytic dsDNA phage, we observe spacer acquisition in the native host Flavobacterium columnare that carries an
more » ... an acquisition-deficient subtype VI-B locus and a complete subtype II-C locus. We characterize acquisition events in both loci and show that the RNA-targeting VI-B locus acquires spacers in trans using acquisition machinery from the DNA-targeting II-C locus. Our observations reinforce the concept of modularity in CRISPR-Cas systems and raise further questions regarding plasticity of adaptation modules.
doi:10.1101/2020.02.20.957498 fatcat:jgifka5r55d7bbsolam45gb6me