Two symmetric arginine residues play distinct roles in Thermus thermophilus Argonaute DNA guide strand-mediated DNA target cleavage

This is the authors' abstract. We don't add key points for this paper.

Significance Argonaute (Ago) proteins function in host defense against foreign mRNA. The Ago-mediated mRNA target cleavage necessitates glutamate finger insertion. Two positively charged residues locate symmetrically around the plugged-in finger, but their functional roles are unclear for Thermus thermophilus Ago ( Tt Ago), a prokaryotic Ago protein. Surprisingly, our simulations and site-mutagenesis experiments indicated that, in contrast to the equivalent roles of symmetrical positively charged residues in Kluyveromyces polysporus Ago (a eukaryotic Ago protein), in Tt Ago, only R545 is critical for mRNA cleavage as a structural anchor to stabilize the plugged-in conformation, whereas R486 plays a negligible role. These differences provide a molecular basis of the distinct glutamate finger functions of Ago proteins in different organisms.