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bioRxiv · 10.1101/2020.02.20.957498

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

Hoikkala, V.·Ravantti, J. J.·Diez-Villasenor, C.·Tiirola, M.·Conrad, R.·McBride, M. J.·Sundberg, L.-R.
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Abstract

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 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.

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Hoikkala, V., Ravantti, J. J., Diez-Villasenor, C., Tiirola, M., Conrad, R., McBride, M. J., Sundberg, L.-R.. 2020-02-20. Cooperation between CRISPR-Cas types enables adaptation in an RNA-targeting system. https://doi.org/10.1101/2020.02.20.957498

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