Structural basis of PETISCO complex assembly during piRNA biogenesis in C. elegans

Piwi-interacting RNAs (piRNAs) constitute a class of small RNAs that bind PIWI proteins and are essential to repress transposable elements in the animal germline, thereby promoting genome stability and maintaining fertility. C. elegans piRNAs (21U RNAs) are transcribed individually from minigenes as precursors that require processing. This process depends on the PETISCO complex, consisting of four proteins: IFE-3, TOFU-6, PID-3, and ERH-2. Determination of structures of the TOFU-6/PID-3 and PID-3/ERH-2 subcomplexes, allows us to propose a model for the formation of the TOFU-6/PID-3/ERH-2 core complex.