title: The making of a slicer: activation of human Argonaute-1.
abstract: Argonautes are the central protein component in small RNA silencing pathways. Of the four human Argonautes (hAgo1-hAgo4) only hAgo2 is an active slicer. We determined the structure of hAgo1 bound to endogenous copurified RNAs to 1.75 Å resolution and hAgo1 loaded with let-7 microRNA to 2.1 Å. Both structures are strikingly similar to the structures of hAgo2. A conserved catalytic tetrad within the PIWI domain of hAgo2 is required for its slicing activity. Completion of the tetrad, combined with a mutation on a loop adjacent to the active site of hAgo1, results in slicer activity that is substantially enhanced by swapping in the N domain of hAgo2. hAgo3, with an intact tetrad, becomes an active slicer by swapping the N domain of hAgo2 without additional mutations. Intriguingly, the elements that make Argonaute an active slicer involve a sophisticated interplay between the active site and more distant regions of the enzyme.
authors.affiliation: W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Faehnle
authors.forename: Elad
authors.initials: E
authors.lastname: Elkayam
authors.forename: Astrid D
authors.initials: AD
authors.lastname: Haase
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Hannon
authors.forename: Leemor
authors.initials: L
authors.lastname: Joshua-Tor
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D060565:Argonaute Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D039642:Eukaryotic Initiation Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism; D061987:Sf9 Cells
chemical_list: C115848:AGO1 protein, human; C466422:AGO2 protein, human; D060565:Argonaute Proteins; D039642:Eukaryotic Initiation Factors; D035683:MicroRNAs; D034741:RNA, Small Interfering; C487931:mirnlet7 microRNA, human