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The contributions of dsRNA structure to Dicer specificity and efficiency.

ABSTRACT: Dicer processes long double-stranded RNA (dsRNA) and pre-microRNAs to generate the functional intermediates (short interfering RNAs and microRNAs) of the RNA interference pathway. Here we identify features of RNA structure that affect Dicer specificity and efficiency. The data presented show that various attributes of the 3' end structure, including overhang length and sequence composition, play a primary role in determining the position of Dicer cleavage in both dsRNA and unimolecular, short hairpin RNA (shRNA). We also demonstrate that siRNA end structure affects overall silencing functionality. Awareness of these new features of Dicer cleavage specificity as it is related to siRNA functionality provides a more detailed understanding of the RNAi mechanism and can shape the development of hairpins with enhanced functionality.

SUBMITTER: Vermeulen A

PROVIDER: S-EPMC1370754 | biostudies-literature | 2005 May

REPOSITORIES: biostudies-literature

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The contributions of dsRNA structure to Dicer specificity and efficiency.

Vermeulen Annaleen A Behlen Linda L Reynolds Angela A Wolfson Alexey A Marshall William S WS Karpilow Jon J Khvorova Anastasia A

RNA (New York, N.Y.) 20050405 5

Dicer processes long double-stranded RNA (dsRNA) and pre-microRNAs to generate the functional intermediates (short interfering RNAs and microRNAs) of the RNA interference pathway. Here we identify features of RNA structure that affect Dicer specificity and efficiency. The data presented show that various attributes of the 3' end structure, including overhang length and sequence composition, play a primary role in determining the position of Dicer cleavage in both dsRNA and unimolecular, short ha ...[more]

PMID: 15811921

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Dicer uses distinct modules for recognizing dsRNA termini.

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The molecular mechanism of dsRNA processing by a bacterial Dicer.

Project description:Members of the ribonuclease (RNase) III family regulate gene expression by processing dsRNAs. It was previously shown that Escherichia coli (Ec) RNase III recognizes dsRNA with little sequence specificity and the cleavage products are mainly 11 nucleotides (nt) long. It was also shown that the mutation of a glutamate (EcE38) to an alanine promotes generation of siRNA-like products typically 22 nt long. To fully characterize substrate specificity and product size of RNase IIIs, we performed in vitro cleavage of dsRNAs by Ec and Aquifex aeolicus (Aa) enzymes and delineated their products by next-generation sequencing. Surprisingly, we found that both enzymes cleave dsRNA at preferred sites, among which a guanine nucleotide was enriched at a specific position (+3G). Based on sequence and structure analyses, we conclude that RNase IIIs recognize +3G via a conserved glutamine (EcQ165/AaQ161) side chain. Abolishing this interaction by mutating the glutamine to an alanine eliminates the observed +3G preference. Furthermore, we identified a second glutamate (EcE65/AaE64), which, when mutated to alanine, also enhances the production of siRNA-like products. Based on these findings, we created a bacterial Dicer that is ideally suited for producing heterogeneous siRNA cocktails to be used in gene silencing studies.

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Sequence determinants of dsRNA processing by DICER

Project description:This SuperSeries is composed of the SubSeries listed below.

2022-12-16 | GSE202535 | GEO

Insights into the structure and RNA-binding specificity of Caenorhabditis elegans Dicer-related helicase 3 (DRH-3).

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Project description:The phenomenon of RNA interference (RNAi) is widely used to develop new approaches for crop improvement and plant protection. Recent investigations show that it is possible to downregulate plant transgenes, as more prone sequences to silencing than endogenous genes, by exogenous application of double-stranded RNAs (dsRNAs) and small interfering RNAs (siRNAs). However, there are scarce data on the specificity of exogenous RNAs. In this study, we explored whether plant transgene suppression is sequence-specific to exogenous dsRNAs and whether similar effects can be caused by exogenous DNAs that are known to be perceived by plants and induce certain epigenetic and biochemical changes. We treated transgenic plants of Arabidopsis thaliana bearing the neomycin phosphotransferase II (NPTII) transgene with specific synthetic NPTII-dsRNAs and non-specific dsRNAs, encoding enhanced green fluorescent protein (EGFP), as well as with DNA molecules mimicking the applied RNAs. None of the EGFP-dsRNA doses resulted in a significant decrease in NPTII transgene expression in the NPTII-transgenic plants, while the specific NPTII-dsRNA significantly reduced NPTII expression in a dose-dependent manner. Long DNAs mimicking dsRNAs and short DNA oligonucleotides mimicking siRNAs did not exhibit a significant effect on NPTII transgene expression. Thus, exogenous NPTII-dsRNAs induced a sequence-specific and RNA-specific transgene-suppressing effect, supporting external application of dsRNAs as a promising strategy for plant gene regulation.

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Sequence determinants of dsRNA processing by DICER [Rescue Experiment]

Project description:RNA silencing relies on specific and efficient processing of dsRNA by DICER which produces microRNAs (miRNAs) and small interfering RNAs (siRNAs). However, our current knowledge of DICER’s specificity is restricted to the secondary structures of its substrates: a dsRNA than 22 bp with a 2-nt 3′ overhang. We recently found evidence pointing to additional sequence-dependent determinant(s) beyond these features. To systematically interrogate the features of precursor miRNAs (pre-miRNAs), we carried out massively parallel assays with over a million pre-miRNA variants. Our analyses revealed a highly conserved cis-acting element, termed the “GYM” motif (paired G, paired pyrimidine, and mismatched C or A) at the cleavage site, which strongly promotes processing at a specific position. We find that the C-terminal double-stranded RNA binding domain (dsRBD) of DICER recognizes the GYM motif. Mutation of the dsRBD alters pre-miRNA cleavage sites and impairs processing in a motif-dependent fashion, which in turn affects the miRNA repertoire in cells. Consistently, integrating the GYM motif into short hairpin RNA (shRNA) or Dicer substrate siRNA (DsiRNA) potentiates RNA interference.

2022-12-16 | GSE202533 | GEO

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