The Experts below are selected from a list of 6075 Experts worldwide ranked by ideXlab platform
Christian Tschudi - One of the best experts on this subject based on the ideXlab platform.
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Function of the trypanosome Argonaute 1 Protein in RNA interference requires the N-terminal RGG domain and arginine 735 in the Piwi domain
The Journal of biological chemistry, 2004Co-Authors: Huafang Shi, Elisabetta Ullu, Christian TschudiAbstract:Argonaute Proteins are central components of RNA interference (RNAi) and related phenomena in a wide variety of eukaryotes, including the early diverging protozoan Trypanosoma brucei. The single T. brucei Argonaute Protein (TbAGO1) is in a complex with small interfering RNAs (siRNAs), and a fraction of this ribonucleoProtein particle is associated with polyribosomes. In this study, we generated a panel of insertion, deletion, and single point mutants of TbAGO1 and assayed them in vivo for their function in RNAi. In addition to the signature domains of Argonaute Proteins, PAZ and Piwi, TbAGO1 has an N-terminal domain with a high abundance of RGG repeats. Deletion of the N-terminal domain blocked association of AGO1 with polyribosomes and severely affected mRNA cleavage. Nevertheless, the mutant Protein was in a complex with siRNAs. In contrast, deletion of the Piwi domain led to a loss of siRNAs but did not abolish polyribosome association. Site-directed mutagenesis of conserved amino acids in the Piwi domain identified arginine 735 as essential for RNAi. Although the R735A mutant bound siRNAs and associated with polyribosomes, it displayed a severe defect in the cleavage of target mRNA.
Huafang Shi - One of the best experts on this subject based on the ideXlab platform.
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Function of the trypanosome Argonaute 1 Protein in RNA interference requires the N-terminal RGG domain and arginine 735 in the Piwi domain
The Journal of biological chemistry, 2004Co-Authors: Huafang Shi, Elisabetta Ullu, Christian TschudiAbstract:Argonaute Proteins are central components of RNA interference (RNAi) and related phenomena in a wide variety of eukaryotes, including the early diverging protozoan Trypanosoma brucei. The single T. brucei Argonaute Protein (TbAGO1) is in a complex with small interfering RNAs (siRNAs), and a fraction of this ribonucleoProtein particle is associated with polyribosomes. In this study, we generated a panel of insertion, deletion, and single point mutants of TbAGO1 and assayed them in vivo for their function in RNAi. In addition to the signature domains of Argonaute Proteins, PAZ and Piwi, TbAGO1 has an N-terminal domain with a high abundance of RGG repeats. Deletion of the N-terminal domain blocked association of AGO1 with polyribosomes and severely affected mRNA cleavage. Nevertheless, the mutant Protein was in a complex with siRNAs. In contrast, deletion of the Piwi domain led to a loss of siRNAs but did not abolish polyribosome association. Site-directed mutagenesis of conserved amino acids in the Piwi domain identified arginine 735 as essential for RNAi. Although the R735A mutant bound siRNAs and associated with polyribosomes, it displayed a severe defect in the cleavage of target mRNA.
Elisabetta Ullu - One of the best experts on this subject based on the ideXlab platform.
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Function of the trypanosome Argonaute 1 Protein in RNA interference requires the N-terminal RGG domain and arginine 735 in the Piwi domain
The Journal of biological chemistry, 2004Co-Authors: Huafang Shi, Elisabetta Ullu, Christian TschudiAbstract:Argonaute Proteins are central components of RNA interference (RNAi) and related phenomena in a wide variety of eukaryotes, including the early diverging protozoan Trypanosoma brucei. The single T. brucei Argonaute Protein (TbAGO1) is in a complex with small interfering RNAs (siRNAs), and a fraction of this ribonucleoProtein particle is associated with polyribosomes. In this study, we generated a panel of insertion, deletion, and single point mutants of TbAGO1 and assayed them in vivo for their function in RNAi. In addition to the signature domains of Argonaute Proteins, PAZ and Piwi, TbAGO1 has an N-terminal domain with a high abundance of RGG repeats. Deletion of the N-terminal domain blocked association of AGO1 with polyribosomes and severely affected mRNA cleavage. Nevertheless, the mutant Protein was in a complex with siRNAs. In contrast, deletion of the Piwi domain led to a loss of siRNAs but did not abolish polyribosome association. Site-directed mutagenesis of conserved amino acids in the Piwi domain identified arginine 735 as essential for RNAi. Although the R735A mutant bound siRNAs and associated with polyribosomes, it displayed a severe defect in the cleavage of target mRNA.
Christophe Antoniewsk - One of the best experts on this subject based on the ideXlab platform.
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The Cricket Paralysis Virus Suppressor Inhibits microRNA Silencing Mediated by the Drosophila Argonaute-2 Protein
PLoS ONE, 2015Co-Authors: Corinne Besnard-guérin, Caroline Jacquier, Josette Pidoux, Safia Deddouche, Christophe AntoniewskAbstract:Small RNAs are potent regulators of gene expression. They also act in defense pathways against invading nucleic acids such as transposable elements or viruses. To counteract these defenses, viruses have evolved viral suppressors of RNA silencing (VSRs). Plant viruses encoded VSRs interfere with siRNAs or miRNAs by targeting common mediators of these two pathways. In contrast, VSRs identified in insect viruses to date only interfere with the siRNA pathway whose effector Argonaute Protein is Argonaute-2 (Ago-2). Although a majority of Drosophila miRNAs exerts their silencing activity through their loading into the Argonaute-1 Protein, recent studies highlighted that a fraction of miRNAs can be loaded into Ago-2, thus acting as siRNAs. In light of these recent findings, we reexamined the role of insect VSRs on Ago-2-mediated miRNA silencing in Drosophila melanogaster. Using specific reporter systems in cultured Schneider-2 cells and transgenic flies, we showed here that the Cricket Paralysis virus VSR CrPV1-A but not the Flock House virus B2 VSR abolishes silencing by miRNAs loaded into the Ago-2 Protein. Thus, our results provide the first evidence that insect VSR have the potential to directly interfere with the miRNA silencing pathway.
Corinne Besnard-guérin - One of the best experts on this subject based on the ideXlab platform.
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The Cricket Paralysis Virus Suppressor Inhibits microRNA Silencing Mediated by the Drosophila Argonaute-2 Protein
PLoS ONE, 2015Co-Authors: Corinne Besnard-guérin, Caroline Jacquier, Josette Pidoux, Safia Deddouche, Christophe AntoniewskAbstract:Small RNAs are potent regulators of gene expression. They also act in defense pathways against invading nucleic acids such as transposable elements or viruses. To counteract these defenses, viruses have evolved viral suppressors of RNA silencing (VSRs). Plant viruses encoded VSRs interfere with siRNAs or miRNAs by targeting common mediators of these two pathways. In contrast, VSRs identified in insect viruses to date only interfere with the siRNA pathway whose effector Argonaute Protein is Argonaute-2 (Ago-2). Although a majority of Drosophila miRNAs exerts their silencing activity through their loading into the Argonaute-1 Protein, recent studies highlighted that a fraction of miRNAs can be loaded into Ago-2, thus acting as siRNAs. In light of these recent findings, we reexamined the role of insect VSRs on Ago-2-mediated miRNA silencing in Drosophila melanogaster. Using specific reporter systems in cultured Schneider-2 cells and transgenic flies, we showed here that the Cricket Paralysis virus VSR CrPV1-A but not the Flock House virus B2 VSR abolishes silencing by miRNAs loaded into the Ago-2 Protein. Thus, our results provide the first evidence that insect VSR have the potential to directly interfere with the miRNA silencing pathway.