While C. elegans is one of the key model organisms for studying small RNA biology, the mechanism of piRNA processing has remained a mystery. The research teams of Sebastian Falk (Max Perutz Labs, Vienna) and René Ketting (IMB, Mainz) discovered PUCH, an enzyme complex responsible for mediating the 5' processing of piRNAs in C. elegans.

Remarkably, PUCH is a unique enzyme complex comprising three Schlafen domain-containing proteins that assemble in a novel manner, forming an active endoribonuclease.

Interestingly, despite its dissimilarity to the piRNA-processing enzymes in flies and mice, PUCH is also found on the mitochondrial surface, suggesting that mitochondrial localization is crucial for activity.

—
Read the paper