86
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Molecular insights into miRNA processing by Arabidopsis thaliana SERRATE

      research-article
      1 , 2 , 3 , 1 , 2 , *
      Nucleic Acids Research
      Oxford University Press

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          In plant, primary transcripts (pri-miRNAs) transcribed from miRNA genes by RNA polymerase II are first processed into stem-loop pre-miRNAs and further chopped into ∼21 nt long miRNAs by RNase III-like enzyme DCL1. SERRATE (SE) protein is an essential component for miRNA processing by assisting DCL1 for accurate cleavage. Here we report the crystal structure of Arabidopsis SE core (residues 194–543) at 2.7 Å. SE core adopts the ‘walking man-like’ topology with N-terminal α helices, C-terminal non-canonical zinc-finger domain and novel Middle domain resembling the leading leg, the lagging leg and the body, respectively. Pull-down assay shows that SE core provides the platform for HYL1 and DCL1 binding, whereas in vitro RNA binding and in vivo mutant rescue experiments suggest that the non-canonical zinc-finger domain coupled with C-terminal tail binds miRNA precursors. SE presumably works as a scaffold-like protein capable of binding both protein and RNA to guide the positioning of miRNA precursor toward DCL1 catalytic site within miRNA processing machinery in plant.

          Related collections

          Most cited references14

          • Record: found
          • Abstract: found
          • Article: not found

          Argonaute2 is the catalytic engine of mammalian RNAi.

          Gene silencing through RNA interference (RNAi) is carried out by RISC, the RNA-induced silencing complex. RISC contains two signature components, small interfering RNAs (siRNAs) and Argonaute family proteins. Here, we show that the multiple Argonaute proteins present in mammals are both biologically and biochemically distinct, with a single mammalian family member, Argonaute2, being responsible for messenger RNA cleavage activity. This protein is essential for mouse development, and cells lacking Argonaute2 are unable to mount an experimental response to siRNAs. Mutations within a cryptic ribonuclease H domain within Argonaute2, as identified by comparison with the structure of an archeal Argonaute protein, inactivate RISC. Thus, our evidence supports a model in which Argonaute contributes "Slicer" activity to RISC, providing the catalytic engine for RNAi.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Human Argonaute2 mediates RNA cleavage targeted by miRNAs and siRNAs.

            Argonaute proteins associate with small RNAs that guide mRNA degradation, translational repression, or a combination of both. The human Argonaute family has eight members, four of which (Ago1 through Ago4) are closely related and coexpressed in many cell types. To understand the biological function of the different Ago proteins, we set out to determine if Ago1 through Ago4 are associated with miRNAs as well as RISC activity in human cell lines. Our results suggest that miRNAs are incorporated indiscriminately of their sequence into Ago1 through Ago4 containing microRNPs (miRNPs). Purification of the FLAG/HA-epitope-tagged Ago containing complexes from different human cell lines revealed that endonuclease activity is exclusively associated with Ago2. Exogenously introduced siRNAs also associate with Ago2 for guiding target RNA cleavage. The specific role of Ago2 in guiding target RNA cleavage was confirmed independently by siRNA-based depletion of individual Ago members in combination with a sensitive positive-readout reporter assay.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              A three-dimensional view of the molecular machinery of RNA interference.

              In eukaryotes, small non-coding RNAs regulate gene expression, helping to control cellular metabolism, growth and differentiation, to maintain genome integrity, and to combat viruses and mobile genetic elements. These pathways involve two specialized ribonucleases that control the production and function of small regulatory RNAs. The enzyme Dicer cleaves double-stranded RNA precursors, generating short interfering RNAs and microRNAs in the cytoplasm. These small RNAs are transferred to Argonaute proteins, which guide the sequence-specific silencing of messenger RNAs that contain complementary sequences by either enzymatically cleaving the mRNA or repressing its translation. The molecular structures of Dicer and the Argonaute proteins, free and bound to small RNAs, have offered exciting insights into the molecular mechanisms that are central to RNA silencing pathways.
                Bookmark

                Author and article information

                Journal
                Nucleic Acids Res
                nar
                nar
                Nucleic Acids Research
                Oxford University Press
                0305-1048
                1362-4962
                September 2011
                September 2011
                17 June 2011
                17 June 2011
                : 39
                : 17
                : 7828-7836
                Affiliations
                1Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, 2Structural Biology Group and 3Host-Pathogen Interaction Group, Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604, Singapore
                Author notes
                *To whom correspondence should be addressed. Tel: (65) 68727409; Fax: (65) 68727007; Email: adam@ 123456tll.org.sg

                Present address: Hong-Ying Chen, Mechanobiology Institute, National University of Singapore, Engineering Drive 1, Singapore 117411, Singapore.

                Article
                gkr428
                10.1093/nar/gkr428
                3177193
                21685453
                b0f1fe70-206d-4ed7-98e3-ccc345d7ef44
                © The Author(s) 2011. Published by Oxford University Press.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 2 April 2011
                : 6 May 2011
                : 11 May 2011
                Page count
                Pages: 9
                Categories
                Structural Biology

                Genetics
                Genetics

                Comments

                Comment on this article