title: A Dynamic Search Process Underlies MicroRNA Targeting.
abstract: Argonaute proteins play a central role in mediating post-transcriptional gene regulation by microRNAs (miRNAs). Argonautes use the nucleotide sequences in miRNAs as guides for identifying target messenger RNAs for repression. Here, we used single-molecule FRET to directly visualize how human Argonaute-2 (Ago2) searches for and identifies target sites in RNAs complementary to its miRNA guide. Our results suggest that Ago2 initially scans for target sites with complementarity to nucleotides 2-4 of the miRNA. This initial transient interaction propagates into a stable association when target complementarity extends to nucleotides 2-8. This stepwise recognition process is coupled to lateral diffusion of Ago2 along the target RNA, which promotes the target search by enhancing the retention of Ago2 on the RNA. The combined results reveal the mechanisms that Argonaute likely uses to efficiently identify miRNA target sites within the vast and dynamic agglomeration of RNA molecules in the living cell.
authors.affiliation: Kavli Institute of NanoScience, Department of BioNanoScience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Stanley D
authors.initials: SD
authors.lastname: Chandradoss
authors.affiliation: Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
authors.forename: Nicole T
authors.initials: NT
authors.lastname: Schirle
authors.affiliation: Kavli Institute of NanoScience, Department of BioNanoScience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Malwina
authors.initials: M
authors.lastname: Szczepaniak
authors.affiliation: Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: MacRae
authors.affiliation: Kavli Institute of NanoScience, Department of BioNanoScience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, The Netherlands.
authors.forename: Chirlmin
authors.initials: C
authors.lastname: Joo
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D004058:Diffusion; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D008954:Models, Biological; D013816:Thermodynamics
chemical_list: C466422:AGO2 protein, human; D060565:Argonaute Proteins; D035683:MicroRNAs