Happy to share our latest piece of work on the PARIS bacterial immune system. We performed a detailed characterization of the AriB Toprim nuclease, the effector of PARIS immunity. www.biorxiv.org/content/10.1... - ThreadSky

dbikard.bsky.social • 19 days ago

Happy to share our latest piece of work on the PARIS bacterial immune system. We performed a detailed characterization of the AriB Toprim nuclease, the effector of PARIS immunity.

https://www.biorxiv.org/content/10.1101/2025.02.04.636281v1

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dbikard.bsky.social•19 days ago

We previously showed how AriB cleaves the E. coli Lysine tRNA when immunity is triggered, blocking translation and phage propagation: https://www.nature.com/articles/s41586-024-07874-3

We now show that AriB also efficiently cleaves one the Threonine tRNAs, as well as a few other tRNAs with lower efficiency.

dbikard.bsky.social•19 days ago

AriB is not the only anti-phage protein targeting this central molecule of translation. CRISPR-Cas13, prrC, Retron-Eco7, toxSAS CapRel and FaRel, RemAIN and more have also been found to target tRNAs!

dbikard.bsky.social•19 days ago

But phages are not phazed :-) Some of them encode their own tRNA variants in order to bypass this immunity mechanism. This includes T5 which carries 24 tRNAs including a Lysine and a Threonine tRNA with mutations that block AriB cleavage.

dbikard.bsky.social•19 days ago

We showed with @artemisaev.bsky.social that expressing the Lysine, Threonine and Asparagine tRNA from T5 can fully rescue E. coli growth when PARIS is triggered.

dbikard.bsky.social•19 days ago

We then investigated the sequence determinants of AriB tRNA recognition. tRNA have a lot of base modifications which can influence their recognition by nucleases as was described for prrC: https://www.sciencedirect.com/science/article/pii/S0022283600942827?via%3Dihub

dbikard.bsky.social•19 days ago

We found that base modifications are not required for AriB recognition. AriB will even efficiently a fully unmodified in vitro transcript. Specific base interactions in the stem of the anti-codon stem-loop are however critical.

isabelott.bsky.social•11 days ago

neat stuff!! tagging for #MEvoSky

pauljaschke.bsky.social•18 days ago

Nice work!

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