Rapid and cost-effective screening of CRISPR/Cas9-induced mutants by DNA-guided Argonaute nuclease

Molecular mechanism for target recognition, dimerization, and activation of Pyrococcus furiosus Argonaute

The Argonaute nuclease from the thermophilic archaeon Pyrococcus furiosus (PfAgo) contributes to host defense and represents a promising biotechnology tool. Here, we report the structure of a PfAgo-guide DNA-target DNA ternary complex at the cleavage-compatible state. The ternary complex is predominantly dimerized, and the dimerization is solely mediated by PfAgo at PIWI-MID, PIWI-PIWI, and PAZ-N interfaces. Additionally, PfAgo accommodates a short 14-bp guide-target DNA duplex with a wedge-type N domain and specifically recognizes 5'-phosphorylated guide DNA. In contrast, the PfAgo-guide DNA binary complex is monomeric, and the engagement of target DNA with 14-bp complementarity induces sufficient dimerization and activation of PfAgo, accompanied by movement of PAZ and N domains. A closely related Argonaute from Thermococcus thioreducens adopts a similar dimerization configuration with an additional zinc finger formed at the dimerization interface. Dimerization of both Argonautes stabilizes the catalytic loops, highlighting the important role of Argonaute dimerization in the activation and target cleavage.

Prokaryotic Argonaute Proteins as a Tool for Biotechnology

Programmable nucleases are the most important tool for manipulating the genes and genomes of both prokaryotes and eukaryotes. Since the end of the 20th century, many approaches were developed for specific modification of the genome. The review briefly considers the advantages and disadvantages of the main genetic editors known to date. The main attention is paid to programmable nucleases from the family of prokaryotic Argonaute proteins. Argonaute proteins can recognize and cleave DNA sequences using small complementary guide molecules and play an important role in protecting prokaryotic cells from invading DNA. Argonaute proteins have already found applications in biotechnology for targeted cleavage and detection of nucleic acids and can potentially be used for genome editing.