Programmable RNA recognition using a CRISPR-associated Argonaute.

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Argonaute proteins (Agos) are crucial for gene regulation in eukaryotes, but their roles in prokaryotes are less understood.
• Bacterial Agos, often linked to CRISPR systems, utilize unique guide RNAs (gRNAs) for nucleic acid targeting.

Purpose of the Study:

• To investigate the impact of 5-bromo-2'-deoxyuridine (BrdU) modification on bacterial Argonaute-gRNA complexes.
• To enhance the specificity and affinity of CRISPR-associated Argonaute proteins for RNA targets.
• To explore the potential of modified Argonaute-gRNA complexes as a tool for RNA detection.

Main Methods:

• Reconstitution of CRISPR-associated *Marinitoga piezophila* Argonaute-gRNA complexes (MpAgo RNPs) with 5'-BrdU-modified gRNAs.
• In vitro characterization of RNP complex stability, specificity, and RNA-binding affinity.
• Mapping of gRNA seed regions and identification of key nucleotides for targeting specificity.
• Demonstration of single-nucleotide discrimination capabilities of MpAgo RNPs.
• Application of MpAgo RNPs for detecting specific edited RNAs in complex mixtures.

Main Results:

• 5'-BrdU modification significantly stabilizes MpAgo RNPs and enhances RNA target specificity and affinity.
• Key gRNA nucleotides influencing targeting specificity were identified.
• MpAgo RNPs demonstrated the ability to distinguish RNA substrates differing by a single nucleotide.
• The platform successfully detected specific adenosine-to-inosine-edited RNAs.

Conclusions:

• 5'-BrdU modification is a key factor in optimizing bacterial Argonaute-gRNA complex function.
• Modified MpAgo RNPs offer a highly specific and programmable platform for RNA targeting.
• This study advances the understanding of Argonaute-RNA interactions and provides a novel tool for RNA biology research.