title: Reconstitution of an Argonaute-dependent small RNA biogenesis pathway reveals a handover mechanism involving the RNA exosome and the exonuclease QIP.
abstract: Argonaute proteins are required for the biogenesis of some small RNAs (sRNAs), including the PIWI-interacting RNAs and some microRNAs. How Argonautes mediate maturation of sRNAs independent of their slicer activity is not clear. The maturation of the Neurospora microRNA-like sRNA, milR-1, requires the Argonaute protein QDE-2, Dicer, and QIP. Here, we reconstitute this Argonaute-dependent sRNA biogenesis pathway in vitro and discover that the RNA exosome is also required for milR-1 production. Our results demonstrate that QDE-2 mediates milR-1 maturation by recruiting exosome and QIP and by determining the size of milR-1. The exonuclease QIP first separates the QDE-2-bound pre-milR-1 duplex and then mediates 3' to 5' trimming and maturation of pre-milRNA together with exosome using a handover mechanism. In addition, exosome is also important for the decay of sRNAs. Together, our results establish a biochemical mechanism of an Argonaute-dependent sRNA biogenesis pathway and critical roles of exosome in sRNA processing.
authors.affiliation: Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Xue
authors.forename: Haiyan
authors.initials: H
authors.lastname: Yuan
authors.forename: Jinhu
authors.initials: J
authors.lastname: Guo
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
mesh_terms: D060565:Argonaute Proteins / Q000502:physiology*; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D009492:Neurospora crassa / Q000235:genetics*; D012322:RNA Precursors / Q000096:biosynthesis / Q000378:metabolism; D012331:RNA, Fungal / Q000378:metabolism*; D058727:RNA, Small Untranslated / Q000378:metabolism*; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism / Q000502:physiology
chemical_list: D060565:Argonaute Proteins; D005656:Fungal Proteins; C406184:QDE-2 protein, Neurospora crassa; D012322:RNA Precursors; D012331:RNA, Fungal; D058727:RNA, Small Untranslated; D005095:Exoribonucleases; D043244:Ribonuclease III