6n4o: Difference between revisions
No edit summary |
No edit summary |
||
Line 3: | Line 3: | ||
<StructureSection load='6n4o' size='340' side='right'caption='[[6n4o]], [[Resolution|resolution]] 2.90Å' scene=''> | <StructureSection load='6n4o' size='340' side='right'caption='[[6n4o]], [[Resolution|resolution]] 2.90Å' scene=''> | ||
== Structural highlights == | == Structural highlights == | ||
<table><tr><td colspan='2'>[[6n4o]] is a 3 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6N4O OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6N4O FirstGlance]. <br> | <table><tr><td colspan='2'>[[6n4o]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Human Human]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6N4O OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6N4O FirstGlance]. <br> | ||
</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6n4o FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6n4o OCA], [http://pdbe.org/6n4o PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6n4o RCSB], [http://www.ebi.ac.uk/pdbsum/6n4o PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6n4o ProSAT]</span></td></tr> | </td></tr><tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">AGO2, EIF2C2 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 HUMAN])</td></tr> | ||
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6n4o FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6n4o OCA], [http://pdbe.org/6n4o PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6n4o RCSB], [http://www.ebi.ac.uk/pdbsum/6n4o PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6n4o ProSAT]</span></td></tr> | |||
</table> | </table> | ||
== Function == | == Function == | ||
Line 12: | Line 13: | ||
microRNAs (miRNAs) guide Argonaute proteins to mRNAs targeted for repression. Target recognition occurs primarily through the miRNA seed region, composed of guide (g) nucleotides g2-g8. However, nucleotides beyond the seed are also important for some known miRNA-target interactions. Here, we report the structure of human Argonaute2 (Ago2) engaged with a target RNA recognized through both miRNA seed and supplementary (g13-g16) regions. Ago2 creates a "supplementary chamber" that accommodates up to five miRNA-target base pairs. Seed and supplementary chambers are adjacent to each other and can be bridged by an unstructured target loop of 1-15 nucleotides. Opening of the supplementary chamber may be constrained by tension in the miRNA 3' tail, as increases in miRNA length stabilize supplementary interactions. Contrary to previous reports, we demonstrate that optimal supplementary interactions can increase target affinity > 20-fold. These results provide a mechanism for extended miRNA targeting, suggest a function for 3' isomiRs in tuning miRNA targeting specificity, and indicate that supplementary interactions may contribute more to target recognition than is widely appreciated. | microRNAs (miRNAs) guide Argonaute proteins to mRNAs targeted for repression. Target recognition occurs primarily through the miRNA seed region, composed of guide (g) nucleotides g2-g8. However, nucleotides beyond the seed are also important for some known miRNA-target interactions. Here, we report the structure of human Argonaute2 (Ago2) engaged with a target RNA recognized through both miRNA seed and supplementary (g13-g16) regions. Ago2 creates a "supplementary chamber" that accommodates up to five miRNA-target base pairs. Seed and supplementary chambers are adjacent to each other and can be bridged by an unstructured target loop of 1-15 nucleotides. Opening of the supplementary chamber may be constrained by tension in the miRNA 3' tail, as increases in miRNA length stabilize supplementary interactions. Contrary to previous reports, we demonstrate that optimal supplementary interactions can increase target affinity > 20-fold. These results provide a mechanism for extended miRNA targeting, suggest a function for 3' isomiRs in tuning miRNA targeting specificity, and indicate that supplementary interactions may contribute more to target recognition than is widely appreciated. | ||
Beyond the seed: structural basis for supplementary microRNA targeting by human Argonaute2.,Sheu-Gruttadauria J, Xiao Y, Gebert LF, MacRae IJ EMBO J. 2019 | Beyond the seed: structural basis for supplementary microRNA targeting by human Argonaute2.,Sheu-Gruttadauria J, Xiao Y, Gebert LF, MacRae IJ EMBO J. 2019 Jul 1;38(13):e101153. doi: 10.15252/embj.2018101153. Epub 2019 Apr, 26. PMID:31268608<ref>PMID:31268608</ref> | ||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | ||
</div> | </div> | ||
<div class="pdbe-citations 6n4o" style="background-color:#fffaf0;"></div> | <div class="pdbe-citations 6n4o" style="background-color:#fffaf0;"></div> | ||
==See Also== | |||
*[[Eukaryotic initiation factor 3D structures|Eukaryotic initiation factor 3D structures]] | |||
== References == | == References == | ||
<references/> | <references/> | ||
__TOC__ | __TOC__ | ||
</StructureSection> | </StructureSection> | ||
[[Category: Human]] | |||
[[Category: Large Structures]] | [[Category: Large Structures]] | ||
[[Category: MacRae, I J]] | [[Category: MacRae, I J]] |
Revision as of 10:58, 23 October 2019
Human Argonaute2-miR-122 bound to a seed and supplementary paired targetHuman Argonaute2-miR-122 bound to a seed and supplementary paired target
Structural highlights
Function[AGO2_HUMAN] Required for RNA-mediated gene silencing (RNAi) by the RNA-induced silencing complex (RISC). The 'minimal RISC' appears to include EIF2C2/AGO2 bound to a short guide RNA such as a microRNA (miRNA) or short interfering RNA (siRNA). These guide RNAs direct RISC to complementary mRNAs that are targets for RISC-mediated gene silencing. The precise mechanism of gene silencing depends on the degree of complementarity between the miRNA or siRNA and its target. Binding of RISC to a perfectly complementary mRNA generally results in silencing due to endonucleolytic cleavage of the mRNA specifically by EIF2C2/AGO2. Binding of RISC to a partially complementary mRNA results in silencing through inhibition of translation, and this is independent of endonuclease activity. May inhibit translation initiation by binding to the 7-methylguanosine cap, thereby preventing the recruitment of the translation initiation factor eIF4-E. May also inhibit translation initiation via interaction with EIF6, which itself binds to the 60S ribosomal subunit and prevents its association with the 40S ribosomal subunit. The inhibition of translational initiation leads to the accumulation of the affected mRNA in cytoplasmic processing bodies (P-bodies), where mRNA degradation may subsequently occur. In some cases RISC-mediated translational repression is also observed for miRNAs that perfectly match the 3' untranslated region (3'-UTR). Can also up-regulate the translation of specific mRNAs under certain growth conditions. Binds to the AU element of the 3'-UTR of the TNF (TNF-alpha) mRNA and up-regulates translation under conditions of serum starvation. Also required for transcriptional gene silencing (TGS), in which short RNAs known as antigene RNAs or agRNAs direct the transcriptional repression of complementary promoter regions.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] Publication Abstract from PubMedmicroRNAs (miRNAs) guide Argonaute proteins to mRNAs targeted for repression. Target recognition occurs primarily through the miRNA seed region, composed of guide (g) nucleotides g2-g8. However, nucleotides beyond the seed are also important for some known miRNA-target interactions. Here, we report the structure of human Argonaute2 (Ago2) engaged with a target RNA recognized through both miRNA seed and supplementary (g13-g16) regions. Ago2 creates a "supplementary chamber" that accommodates up to five miRNA-target base pairs. Seed and supplementary chambers are adjacent to each other and can be bridged by an unstructured target loop of 1-15 nucleotides. Opening of the supplementary chamber may be constrained by tension in the miRNA 3' tail, as increases in miRNA length stabilize supplementary interactions. Contrary to previous reports, we demonstrate that optimal supplementary interactions can increase target affinity > 20-fold. These results provide a mechanism for extended miRNA targeting, suggest a function for 3' isomiRs in tuning miRNA targeting specificity, and indicate that supplementary interactions may contribute more to target recognition than is widely appreciated. Beyond the seed: structural basis for supplementary microRNA targeting by human Argonaute2.,Sheu-Gruttadauria J, Xiao Y, Gebert LF, MacRae IJ EMBO J. 2019 Jul 1;38(13):e101153. doi: 10.15252/embj.2018101153. Epub 2019 Apr, 26. PMID:31268608[23] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
|
|