title: Structural insights into small RNA sorting and mRNA target binding by Arabidopsis Argonaute Mid domains.
abstract: The RISC-associated Argonaute (Ago) proteins play the catalytic role for RISC-mediated gene regulation by selecting small RNAs and subsequent targeting and cleavage of complementary mRNAs. Ago Mid domains are proposed to play essential roles in small RNA sorting. Here, we report the crystal structures of Arabidopsis Ago1 Mid domain and its chimera mutant with part of Ago1 replaced by Ago4. The structures demonstrate that a single amino insertion in the nucleotide specificity loop of AtAgo1 will change the nucleotide binding preference of AtAgo1 from "5'-U" to "5'-A". Moreover, we identify a long positively charged groove located along the "5'-end-nucleotide specificity loop" and occupied by several sulfate ions with the distance of 9-11Å distance, indicating a putative mRNA target binding groove.
authors: Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore.
authors: Xingfu
authors: X
authors: Zha
authors: Qingyou
authors: Q
authors: Xia
authors: Y Adam
authors: YA
authors: Yuan
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D060565:Argonaute Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D034443:RNA Transport; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity
chemical_list: C117457:AGO1 protein, Arabidopsis; C471209:AGO4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060565:Argonaute Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C559855:argonaute 2 protein, Arabidopsis