RNA-guided RNA silencing by an 1 Asgard archaeal Argonaute
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ABSTRACT:
ORGANISM(S): Escherichia coli
PROVIDER: GSE267550 | GEO | 2024/05/21
REPOSITORIES: GEO
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Project description:Eukaryotic Argonautes bind small RNAs and use them as guides to find complementary RNA targets and induce gene silencing. Though homologs of eukaryotic Argonautes are present in many bacteria and archaea their small RNA partners and functions are unknown. We found that the Argonaute of Rhodobacter sphaeroides (RsAgo) associates with 15-19 nt small RNAs that correspond to the majority of transcripts. RsAgo also binds single-stranded 22-24 nt DNA molecules that are complementary to the small RNAs and enriched in sequences derived from exogenous plasmids as well as genome-encoded foreign nucleic acids such as transposons and phage genes. Expression of RsAgo in the heterologous E. coli system leads to formation of plasmid–derived small RNA and DNA and plasmid degradation. In a R. sphaeroides mutant lacking RsAgo, expression of plasmid-encoded genes is elevated, while other genes are unaffected. Our results indicate that RNAi-related processes found in eukaryotes are also conserved in bacteria and target foreign nucleic acids. Small RNA and small DNA from purified RsAgo expressed in Rhodobacter sphaeroides ATCC17025 ("strain 25") and E. coli BL21(DE3) Total small RNA (13-30nt) from R. sphaeroides ATCC17025 and ATCC17029 (wild-type; RsAgo mutant; containing either empty or RsAgo-expressing plasmid) Total ribosomal RNA-depleted RNA from wild type or RsAgo mutant R. sphaeroides ATCC17025
2013-09-12 | E-GEOD-49865 | biostudies-arrayexpress
Project description:Eukaryotic Argonautes bind small RNAs and use them as guides to find complementary RNA targets and induce gene silencing. Though homologs of eukaryotic Argonautes are present in many bacteria and archaea their small RNA partners and functions are unknown. We found that the Argonaute of Rhodobacter sphaeroides (RsAgo) associates with 15-19 nt small RNAs that correspond to the majority of transcripts. RsAgo also binds single-stranded 22-24 nt DNA molecules that are complementary to the small RNAs and enriched in sequences derived from exogenous plasmids as well as genome-encoded foreign nucleic acids such as transposons and phage genes. Expression of RsAgo in the heterologous E. coli system leads to formation of plasmid–derived small RNA and DNA and plasmid degradation. In a R. sphaeroides mutant lacking RsAgo, expression of plasmid-encoded genes is elevated, while other genes are unaffected. Our results indicate that RNAi-related processes found in eukaryotes are also conserved in bacteria and target foreign nucleic acids.
2013-09-12 | GSE49865 | GEO
Project description:We analyzed the small RNAs bound to the fission yeast RITS and ARC complexes, and to Ago1 in wild-type and ARC mutant cells, to gain insight into the molecular role of ARC. We found that ARC contains longer heterochromatic siRNAs than RITS, and that ARC subunit Arb1 is required for loading small RNAs onto Ago1. Sequencing of 18-28 nt small RNAs from Tas3, Arb1 and Ago1 purifications.
2015-03-01 | E-GEOD-65223 | biostudies-arrayexpress
Project description:Nuclear Argonaute proteins, guided by their bound small RNAs, orchestrate heterochromatin formation at transposon insertions and repetitive genomic loci. The molecular mechanisms that, besides recruiting heterochromatin effector proteins, are required for this silencing process are poorly understood. Here, we show that the SFiNX complex, the central silencing mediator downstream of nuclear Piwi-piRNA complexes in Drosophila, enables co-transcriptional silencing via the formation of molecular condensates. Condensate formation is stimulated by nucleic acid binding and requires SFiNX to form a homodimer. The dynein light chain dLC8, a highly conserved dimerization hub protein, mediates homo-dimerization of SFiNX. Point mutations preventing dLC8-mediated SFiNX dimerization result in transposon de-repression and sterility. dLC8’s function can be bypassed with a heterologous dimerization domain, suggesting that dimerization is a constitutive rather than a regulated feature of SFiNX. We propose that nucleic-acid stimulated condensate formation enables co-transcriptional silencing through the retention of the target RNA at chromatin, thereby allowing effector proteins to establish heterochromatin at the target locus.
2021-02-12 | PXD022010 | Pride
Project description:We analyzed the small RNAs bound to the fission yeast RITS and ARC complexes, and to Ago1 in wild-type and ARC mutant cells, to gain insight into the molecular role of ARC. We found that ARC contains longer heterochromatic siRNAs than RITS, and that ARC subunit Arb1 is required for loading small RNAs onto Ago1.
2015-03-01 | GSE65223 | GEO
Project description: Not available
| S-EPMC5576611 | biostudies-literature
Project description:In the Caenorhabditis elegans germline, thousands of mRNAs are concomitantly expressed with antisense 22G-RNAs, which are loaded into the Argonaute CSR-1. Despite their essential functions for animal fertility and embryonic development, how CSR-1 22G-RNAs are produced remains unknown. Here, we show that CSR-1 slicer activity is primarily involved in triggering the synthesis of small RNAs on the coding sequences of germline mRNAs and post-transcriptionally regulates a fraction of targets. CSR-1-cleaved mRNAs prime the RNA-dependent RNA polymerase, EGO-1, to synthesize 22G-RNAs in phase with ribosome translation in the cytoplasm, in contrast to other 22G-RNAs mostly synthesized in germ granules. Moreover, codon optimality and efficient translation antagonize CSR-1 slicing and 22G-RNAs biogenesis. We propose that codon usage differences encoded into mRNA sequences might be a conserved strategy in eukaryotes to regulate small RNA biogenesis and Argonaute targeting
2021-04-23 | PXD020293 | Pride
Project description: Not available
| S-EPMC5435312 | biostudies-literature
Project description:The assembly of fission yeast pericentromeric heterochromatin and generation of small interfering RNAs (siRNAs) from noncoding centromeric transcripts are mutually dependent processes. How this interdependent positive feedback loop is first triggered is a fundamental unanswered question. Here we show that two distinct Argonaute (Ago1)-dependent pathways mediate small RNA generation. RNA-dependent RNA polymerase complex (RDRC) and Dicer act on specific noncoding RNAs to generate siRNAs by a mechanism that requires the slicer activity of Ago1 but is independent of pre-existing heterochromatin. In the absence of RDRC or Dicer, a distinct class of small RNAs, called primal small RNAs (priRNAs), associate with Ago1. priRNAs are degradation products of abundant transcripts, which bind to Ago1 and target antisense transcripts that result from bidirectional transcription of DNA repeats. Our results suggest that a transcriptome surveillance mechanism based on the random association of RNA degradation products with Argonaute triggers siRNA amplification and heterochromatin assembly within DNA repeats. small RNA profiling in wild type S. pombe cells and in 12 mutant cells
2010-02-23 | E-GEOD-19734 | biostudies-arrayexpress
Project description:RNA interference (RNAi) is a conserved gene silencing process that exists in diverse organisms to protect genome integrity and regulate gene expression. In C. elegans, the majority of RNAi pathway proteins localize to perinuclear, phase-separated germ granules, which are comprised of sub-domains referred to as P granules, Mutator foci, Z granules, and SIMR foci. However, the protein components and function of the newly discovered SIMR foci are unknown. Here we demonstrate that HRDE-2 localizes to SIMR foci and interacts with the germline nuclear RNAi Argonaute HRDE-1. Furthermore, HRDE-1 also localizes to SIMR foci, dependent on HRDE-2, but only in its small RNA unbound state. This germ granule localization is critical to promote the small RNA binding specificity of HRDE-1 and, in the absence of HRDE-2, HRDE-1 exclusively loads CSR-class 22G-RNAs rather than WAGO-class 22G-RNAs, resulting in H3K9me3 deposition on CSR-target genes. Thus, our study demonstrates that HRDE-2 is critical to ensure that the correct small RNAs are used to guide nuclear RNA silencing in the C. elegans germline.
2023-07-27 | MSV000092546 | MassIVE