Structural insights into small RNA sorting and mRNA target binding by Arabidopsis Argonaute Mid domains.

Xingfu Zha, Qingyou Xia, Y Adam Yuan

Department of Biological Sciences and Centre for Bioimaging Sciences, National University of Singapore, Singapore.

FEBS letters 2012 Sep 21

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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. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Citation

Xingfu Zha, Qingyou Xia, Y Adam Yuan. Structural insights into small RNA sorting and mRNA target binding by Arabidopsis Argonaute Mid domains. FEBS letters. 2012 Sep 21;586(19):3200-7