Taking RISCs with Ago hookers

Argonautes are central and common components of crucial effectors of RNA silencing pathways. Although earlier steps in these pathways, such as small RNA biogenesis and their loading into AGO, have been quite well described, our knowledge on regulation of the action of AGO and their partners is still poor. Recent breakthroughs have highlighted the existence in many eukaryotes of an evolutionarily conserved motif, the Ago-hook, in factors implicated in AGO action. Furthermore, it has been shown that certain plant pathogen proteins have co-opted the Ago-hook as a means of evasion of plant defense systems. Here we discuss the roles and properties of Ago-hook proteins in divergent RNAi-related pathways.

► Proteins containing evolutionarily conserved GW-rich motifs are implicated in Argonaute action.
► These Ago-hook factors are involved in diverse RNAi pathways.
► The AGO-hook motifs interact with the 5′ binding pocket of the mid-PIWI domain of Argonautes.
► Some plant pathogens encode silencing suppresors that hijack Ago-hooks to escape the host RNA silencing machinery.