title: Single-Molecule Imaging Reveals that Argonaute Reshapes the Binding Properties of Its Nucleic Acid Guides.
abstract: Argonaute proteins repress gene expression and defend against foreign nucleic acids using short RNAs or DNAs to specify the correct target RNA or DNA sequence. We have developed single-molecule methods to analyze target binding and cleavage mediated by the Argonaute:guide complex, RISC. We find that both eukaryotic and prokaryotic Argonaute proteins reshape the fundamental properties of RNA:RNA, RNA:DNA, and DNA:DNA hybridization—a small RNA or DNA bound to Argonaute as a guide no longer follows the well-established rules by which oligonucleotides find, bind, and dissociate from complementary nucleic acid sequences. Argonautes distinguish substrates from targets with similar complementarity. Mouse AGO2, for example, binds tighter to miRNA targets than its RNAi cleavage product, even though the cleaved product contains more base pairs. By re-writing the rules for nucleic acid hybridization, Argonautes allow oligonucleotides to serve as specificity determinants with thermodynamic and kinetic properties more typical of RNA-binding proteins than of RNA or DNA.
authors.affiliation: RNA Therapeutics Institute, Howard Hughes Medical Institute, and Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: William E
authors.initials: WE
authors.lastname: Salomon
authors.affiliation: RNA Therapeutics Institute, Howard Hughes Medical Institute, and Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Samson M
authors.initials: SM
authors.lastname: Jolly
authors.affiliation: RNA Therapeutics Institute, Howard Hughes Medical Institute, and Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Moore
authors.affiliation: RNA Therapeutics Institute, Howard Hughes Medical Institute, and Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA. Electronic address: phillip.zamore@umassmed.edu.
authors.forename: Phillip D
authors.initials: PD
authors.lastname: Zamore
authors.affiliation: RNA Therapeutics Institute, Howard Hughes Medical Institute, and Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA. Electronic address: victor.serebrov@umassmed.edu.
authors.forename: Victor
authors.initials: V
authors.lastname: Serebrov
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D057054:Molecular Imaging; D009693:Nucleic Acid Hybridization; D034743:RNA-Induced Silencing Complex / Q000378:metabolism; D013816:Thermodynamics; D016963:Thermus thermophilus / Q000378:metabolism; D000094704:RNA, Guide, CRISPR-Cas Systems
chemical_list: D060565:Argonaute Proteins; D001426:Bacterial Proteins; D035683:MicroRNAs; D034743:RNA-Induced Silencing Complex; D000094704:RNA, Guide, CRISPR-Cas Systems; C526735:Ago2 protein, mouse; C542687:mirnlet7 microRNA, mouse