title: Structure of precursor microRNA's terminal loop regulates human Dicer's dicing activity by switching DExH/D domain.
abstract: Almost all pre-miRNAs in eukaryotic cytoplasm are recognized and processed into double-stranded microRNAs by the endonuclease Dicer protein comprising of multiple domains. As a key player in the small RNA induced gene silencing pathway, the major domains of Dicer are conserved among different species with the exception of the N-terminal components. Human Dicer's N-terminal domain has been shown to play an auto-inhibitory function of the protein's dicing activity. Such an auto-inhibition can be released when the human Dicer protein dimerizes with its partner protein, such as TRBP, PACT through the N-terminal DExH/D (ATPase-helicase) domain. The typical feature of a pre-miRNA contains a terminal loop and a stem duplex, which bind to human Dicer's DExH/D (ATPase-helicase) domain and PAZ domain respectively during the dicing reaction. Here, we show that pre-miRNA's terminal loop can regulate human Dicer's enzymatic activity by interacting with the DExH/D (ATPase-helicase) domain. We found that various editing products of pre-miR-151 by the ADAR1P110 protein, an A-to-I editing enzyme that modifies pre-miRNAs sequence, have different terminal loop structures and different activity regulatory effects on human Dicer. Single particle electron microscopy reconstruction revealed that pre-miRNAs with different terminal loop structures induce human Dicer's DExH/D (ATPase-helicase) domain into different conformational states, in correlation with their activity regulatory effects.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China.
authors.forename: Zhongmin
authors.initials: Z
authors.lastname: Liu
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Wang
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D053487:DEAD-box RNA Helicases / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D035683:MicroRNAs / Q000737:chemistry* / Q000235:genetics; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D017393:RNA Editing / Q000235:genetics; D043244:Ribonuclease III / Q000737:chemistry* / Q000235:genetics
chemical_list: D035683:MicroRNAs; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases