The Making of a Slicer: Activation of Human Argonaute-1
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ABSTRACT:
ORGANISM(S): Spodoptera frugiperda
SUBMITTER: Astrid Haase
PROVIDER: E-GEOD-46870 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:The Argonautes are the central protein component in small RNA silencing pathways. Of the four human Argonautes (hAgo1-4) 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 miRNA to 2.1 Å. Both structures are strikingly similar to the structures of hAgo2. A conserved DEDH catalytic tetrad within the PIWI domain of hAgo2 is required for its slicing activity. hAgo3, with an intact tetrad, could be activated by swapping in the N domain of hAgo2, without additional PIWI domain mutations. An additional 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. Intriguingly, the elements that make Argonaute an active slicer involve a sophisticated interplay between the active site and more distant regions of the enzyme.
2013-05-20 | GSE46870 | GEO
Project description:In diverse organisms, the highly-conserved Piwi proteins bind to a complex class of small non-coding RNAs called piRNAs, and are essential for germline stem cell maintenance, transposon silencing, fertility, and offspring viability1. By homology with other Argonautes, Piwi proteins have been proposed and later reported to possess endonuclease activity in vitro, effected by its conserved aspartate catalytic triad2,3. Indeed, mutation of these residues in one of the three mouse PIWI proteins, MILI, affects the production of Line 1 piRNAs and spermatogenesis4. In Drosophila, the conserved slicer function has been proposed to be crucial for all Piwi proteins in piRNA amplification and transposon silencing5. Here, we report in vivo evidence that, in contrast to common belief, the catalytic triad of Piwi is not required for the function of PIwi in the germline for stem cell maintenance, fertility, transposon silencing, or piRNA biogenesis. In addition, it is not required for piRNA biogenesis in the soma where Piwi is the sole Piwi-subfamily protein involved in the process. These observations, together with the recent findings on MILI and MIWI2 triad mutant, indicate that even though the slicer function may be required for a subset of piRNA-mediated process, it is overall inconsequential for the function of Piwi proteins Assess the role of the endonuclease activity of Piwi in all known biological processes that involve Piwi function in Drosophila ovary
2013-02-04 | E-GEOD-34032 | biostudies-arrayexpress
Project description:We solved the crystal structure of human ARGONAUTE1 (hAGO1) bound to endogenous 5'-phosphorylated guide RNAs. To identify structural changes that evolutionarily rendered hAGO1 inactive, we compared our structure with published structures of guide-RNA-containing and cleavage-active hAGO2. Aside from mutation of a catalytic tetrad residue, proline residues at positions 670 and 675 in hAGO1 introduce a kink in the cS7 loop and thereby forming a convex surface within the hAGO1 nucleic-acid-binding channel near the inactive catalytic site. We predicted that even upon restoration of the catalytic tetrad, hAGO1-cS7 sterically hinders the placement of a fully-paired guide-target RNA duplex into the endonuclease active site. Consistent with this hypothesis, reconstitution of the catalytic tetrad (R805H) led to low level hAGO1 cleavage activity, whereas combining R805H with cS7 substitutions (P670S and P675Q) substantially augmented hAGO1 activity. Evolutionary changes to hAGO1 were subtle and readily reversible, suggesting that loading of guide RNA and seed-based miRNA-target RNA pairing constrain its sequence drift. Structure-guided design of mutations that confer slicer activity to hAGO1. RNAs were isolated from recombinant purified hAGO1 and hAGO2, processed from baculovirus-infected Trichoplusia ni insect cells, and then processed for Illumina HiSeq. In addition, total RNA samples from AGO1 baculouvirus infected vs. non-infected Trichoplusia ni cells were isolated and also processed for Illumina HiSeq.
2013-06-20 | E-GEOD-48076 | biostudies-arrayexpress
Project description:In diverse organisms, the highly-conserved Piwi proteins bind to a complex class of small non-coding RNAs called piRNAs, and are essential for germline stem cell maintenance, transposon silencing, fertility, and offspring viability1. By homology with other Argonautes, Piwi proteins have been proposed and later reported to possess endonuclease activity in vitro, effected by its conserved aspartate catalytic triad2,3. Indeed, mutation of these residues in one of the three mouse PIWI proteins, MILI, affects the production of Line 1 piRNAs and spermatogenesis4. In Drosophila, the conserved slicer function has been proposed to be crucial for all Piwi proteins in piRNA amplification and transposon silencing5. Here, we report in vivo evidence that, in contrast to common belief, the catalytic triad of Piwi is not required for the function of PIwi in the germline for stem cell maintenance, fertility, transposon silencing, or piRNA biogenesis. In addition, it is not required for piRNA biogenesis in the soma where Piwi is the sole Piwi-subfamily protein involved in the process. These observations, together with the recent findings on MILI and MIWI2 triad mutant, indicate that even though the slicer function may be required for a subset of piRNA-mediated process, it is overall inconsequential for the function of Piwi proteins
2013-02-04 | GSE34032 | GEO
Project description:The Arabidopsis ARGONAUTE (AGO) protein AGO1 associates with microRNA (miRNA) and specific classes of short-interfering RNA (siRNA). AGO1-small RNA complexes recognize target RNA transcripts through base-pairing interactions and inhibit translation of target RNAs through endonucleolytic cleavage (slicing) or non-degradative mechanisms. The PIWI domain of AGO1 contains a metal-coordinating triad [Asp-Asp-His] (DDH) that is required for slicer activity. Here, we compared the activities of wild type (DDH) and slicer active-site defective (DAH) forms of AGO1 by sequencing small RNA and target transcript RNAs that co-immunoprecipitated with hemagglutinin (HA)-tagged AGO1 proteins. We found that the population of miRNA that associated with both AGO1-DDH and AGO1-DAH proteins largely overlapped, suggesting that cleavage activity does not affect miRNA maturation. In contrast, slicer-defective AGO1-miRNA complexes associated with target RNA more effectively than did wild type AGO1-miRNA. These data indicate that slicer-defective AGO proteins can be used as an approach to capture AGO-small RNA-target RNA ternary complexes more efficiently for genome-wide analyses.
2012-09-28 | GSE40256 | GEO
Project description:The Arabidopsis ARGONAUTE (AGO) protein AGO1 associates with microRNA (miRNA) and specific classes of short-interfering RNA (siRNA). AGO1-small RNA complexes recognize target RNA transcripts through base-pairing interactions and inhibit translation of target RNAs through endonucleolytic cleavage (slicing) or non-degradative mechanisms. The PIWI domain of AGO1 contains a metal-coordinating triad [Asp-Asp-His] (DDH) that is required for slicer activity. Here, we compared the activities of wild type (DDH) and slicer active-site defective (DAH) forms of AGO1 by sequencing small RNA and target transcript RNAs that co-immunoprecipitated with hemagglutinin (HA)-tagged AGO1 proteins. We found that the population of miRNA that associated with both AGO1-DDH and AGO1-DAH proteins largely overlapped, suggesting that cleavage activity does not affect miRNA maturation. In contrast, slicer-defective AGO1-miRNA complexes associated with target RNA more effectively than did wild type AGO1-miRNA. These data indicate that slicer-defective AGO proteins can be used as an approach to capture AGO-small RNA-target RNA ternary complexes more efficiently for genome-wide analyses. AGO1-DDH (wild type) AGO1-DAH (slicer mutant) proteins were immunoprecipitated (N-terminal 3xHA) from Arabidopsis (Columbia) flower (stages 1-12) lysate. Immunoprecipitations were also done from control plants transformed with vector only. Small RNA from immunoprecipitate fractions of vector, AGO1-DDH and AGO1-DAH were sequenced.
2012-09-28 | E-GEOD-40258 | biostudies-arrayexpress
Project description:The Arabidopsis ARGONAUTE (AGO) protein AGO1 associates with microRNA (miRNA) and specific classes of short-interfering RNA (siRNA). AGO1-small RNA complexes recognize target RNA transcripts through base-pairing interactions and inhibit translation of target RNAs through endonucleolytic cleavage (slicing) or non-degradative mechanisms. The PIWI domain of AGO1 contains a metal-coordinating triad [Asp-Asp-His] (DDH) that is required for slicer activity. Here, we compared the activities of wild type (DDH) and slicer active-site defective (DAH) forms of AGO1 by sequencing small RNA and target transcript RNAs that co-immunoprecipitated with hemagglutinin (HA)-tagged AGO1 proteins. We found that the population of miRNA that associated with both AGO1-DDH and AGO1-DAH proteins largely overlapped, suggesting that cleavage activity does not affect miRNA maturation. In contrast, slicer-defective AGO1-miRNA complexes associated with target RNA more effectively than did wild type AGO1-miRNA. These data indicate that slicer-defective AGO proteins can be used as an approach to capture AGO-small RNA-target RNA ternary complexes more efficiently for genome-wide analyses.
2012-09-28 | GSE40258 | GEO
Project description:The Arabidopsis ARGONAUTE (AGO) protein AGO1 associates with microRNA (miRNA) and specific classes of short-interfering RNA (siRNA). AGO1-small RNA complexes recognize target RNA transcripts through base-pairing interactions and inhibit translation of target RNAs through endonucleolytic cleavage (slicing) or non-degradative mechanisms. The PIWI domain of AGO1 contains a metal-coordinating triad [Asp-Asp-His] (DDH) that is required for slicer activity. Here, we compared the activities of wild type (DDH) and slicer active-site defective (DAH) forms of AGO1 by sequencing small RNA and target transcript RNAs that co-immunoprecipitated with hemagglutinin (HA)-tagged AGO1 proteins. We found that the population of miRNA that associated with both AGO1-DDH and AGO1-DAH proteins largely overlapped, suggesting that cleavage activity does not affect miRNA maturation. In contrast, slicer-defective AGO1-miRNA complexes associated with target RNA more effectively than did wild type AGO1-miRNA. These data indicate that slicer-defective AGO proteins can be used as an approach to capture AGO-small RNA-target RNA ternary complexes more efficiently for genome-wide analyses. AGO1-DDH (wild type) AGO1-DAH (slicer mutant) proteins were immunoprecipitated (N-terminal 3xHA) from Arabidopsis (Columbia) flower (stages 1-12) lysate. Immunoprecipitate fractions were treated with nuclease P1 before cleanup to trim free RNA ends, and therefore enrich samples in AGO1 target sites. All samples were treated with Ribominus (Life Technologies) to reduce ribosomal RNA abundance. Transcript fragments from two replicates of AGO1-DDH and AGO1-DAH immunoprecipitates were sequenced. Ribominus-treated total RNA (input controls) was also sequenced for each replicate.
2012-09-28 | E-GEOD-40256 | biostudies-arrayexpress
Project description:We solved the crystal structure of human ARGONAUTE1 (hAGO1) bound to endogenous 5'-phosphorylated guide RNAs. To identify structural changes that evolutionarily rendered hAGO1 inactive, we compared our structure with published structures of guide-RNA-containing and cleavage-active hAGO2. Aside from mutation of a catalytic tetrad residue, proline residues at positions 670 and 675 in hAGO1 introduce a kink in the cS7 loop and thereby forming a convex surface within the hAGO1 nucleic-acid-binding channel near the inactive catalytic site. We predicted that even upon restoration of the catalytic tetrad, hAGO1-cS7 sterically hinders the placement of a fully-paired guide-target RNA duplex into the endonuclease active site. Consistent with this hypothesis, reconstitution of the catalytic tetrad (R805H) led to low level hAGO1 cleavage activity, whereas combining R805H with cS7 substitutions (P670S and P675Q) substantially augmented hAGO1 activity. Evolutionary changes to hAGO1 were subtle and readily reversible, suggesting that loading of guide RNA and seed-based miRNA-target RNA pairing constrain its sequence drift.
2013-06-20 | GSE48076 | GEO
Project description:Piwi-interacting RNAs (piRNAs) silence transposons in animal germ cells. In Drosophila, the reciprocal “Ping-Pong” cycle of piRNA-directed RNA cleavage, catalyzed by the PIWI proteins Aubergine (Aub) and Argonaute3 (AGO3) through their Slicer activity, is believed to expand the population of antisense piRNAs in response to transposon expression. Whether and how the Slicer activity of AGO3/Aub promotes the process of the secondary piRNA amplification remain unclear. Here we generated transgenic flies that could express AGO3 Slicer mutant forms to ellucidate the Slicer activity of AGO3.
2014-06-30 | GSE49436 | GEO