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bioRxiv · 10.1101/2025.03.07.641588

Analysis of tracrRNAs reveals subgroup V2 of type V-K CAST systems

Ziemann, M.·Mitrofanov, A.·Stoeckl, R.·Alkhnbashi, O. S.·Backofen, R.·Hess, W. R.
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Abstract

CRISPR-associated transposons (CAST) consist of an integration between certain class 1 or class 2 CRISPR-Cas systems and Tn7-like transposons. Class 2 type V-K CAST systems are restricted to cyanobacteria. Here, we identified a unique subgroup of type V-K systems through phylogenetic analysis, classified as V-K_V2. Subgroup V-K_V2 CAST systems are characterized by an alternative tracrRNA, the exclusive use of Arc_2-type transcriptional regulators, and distinct differences in TnsB and TnsC proteins. Although the occurrence of V-K_V2 CAST systems is restricted to Nostocales cyanobacteria, it shows signs of horizontal gene transfer, indicating its capability for genetic mobility. The predicted V-K_V2 tracrRNA secondary structure has been integrated into an updated version of the CRISPRtracrRNA program available on GitHub under https://github.com/BackofenLab/CRISPRtracrRNA/releases/tag/2.0.

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Ziemann, M., Mitrofanov, A., Stoeckl, R., Alkhnbashi, O. S., Backofen, R., Hess, W. R.. 2025-03-10. Analysis of tracrRNAs reveals subgroup V2 of type V-K CAST systems. https://doi.org/10.1101/2025.03.07.641588

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