title: Substrate-specific structural rearrangements of human Dicer.
abstract: Dicer has a central role in RNA-interference pathways by cleaving double-stranded RNAs (dsRNAs) to produce small regulatory RNAs. Human Dicer can process long double-stranded and hairpin precursor RNAs to yield short interfering RNAs (siRNAs) and microRNAs (miRNAs), respectively. Previous studies have shown that pre-miRNAs are cleaved more rapidly than pre-siRNAs in vitro and are the predominant natural Dicer substrates. We have used EM and single-particle analysis of Dicer-RNA complexes to gain insight into the structural basis for human Dicer's substrate preference. Our studies show that Dicer traps pre-siRNAs in a nonproductive conformation, whereas interactions of Dicer with pre-miRNAs and dsRNA-binding proteins induce structural changes in the enzyme that enable productive substrate recognition in the central catalytic channel. These findings implicate RNA structure and cofactors in determining substrate recognition and processing efficiency by human Dicer.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Taylor
authors.forename: Enbo
authors.initials: E
authors.lastname: Ma
authors.forename: Hideki
authors.initials: H
authors.lastname: Shigematsu
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cianfrocco
authors.forename: Cameron L
authors.initials: CL
authors.lastname: Noland
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Nagayama
authors.forename: Eva
authors.initials: E
authors.lastname: Nogales
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Doudna
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Wang
mesh_terms: D053487:DEAD-box RNA Helicases / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism; D008854:Microscopy, Electron; D008954:Models, Biological; D008958:Models, Molecular; D011487:Protein Conformation; D012330:RNA, Double-Stranded / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D034741:RNA, Small Interfering / Q000378:metabolism; D043244:Ribonuclease III / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D035683:MicroRNAs; D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; C408087:DICER1 protein, human; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases