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DNAzyme-dependent Analysis of rRNA 2’-O-Methylation
Published on: September 16, 2019
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A DCL3 dicing code within Pol IV-RDR2 transcripts diversifies the siRNA pool guiding RNA-directed DNA methylation
Andrew Loffer1, Jasleen Singh1, Akihito Fukudome1,2
1Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University Bloomington, Bloomington, United States.
Elife
|January 31, 2022
Summary
Plant RNA-directed DNA methylation relies on small interfering RNAs (siRNAs) generated by NUCLEAR RNA POLYMERASE IV (Pol IV) and RNA-DEPENDENT RNA POLYMERASE 2 (RDR2). Their combined activities create a code influencing siRNA size and precursor processing for effective gene silencing.
Area of Science:
- Plant molecular biology
- Epigenetics
- RNA interference
Background:
- Selfish genetic elements in plants are silenced via RNA-directed DNA methylation.
- Short interfering RNAs (siRNAs) guide this silencing process.
- DICER-LIKE 3 (DCL3) processes double-stranded RNA precursors into siRNAs.
Purpose of the Study:
- To investigate how NUCLEAR RNA POLYMERASE IV (Pol IV) and RNA-DEPENDENT RNA POLYMERASE 2 (RDR2) influence siRNA generation.
- To understand the mechanisms determining siRNA size and precursor processing.
- To elucidate how these factors contribute to maximal siRNA coverage at target loci.
Main Methods:
- Analysis of nucleotide initiation by Pol IV.
- Characterization of RDR2 initiation relative to Pol IV transcripts.
- Assessment of RDR2 terminal transferase activity.
- Examination of DCL3 dicing patterns.
Main Results:
- Pol IV initiation nucleotide choice impacts precursor processing.
- RDR2 initiation site and terminal transferase activity generate a code.
- This code dictates which precursor end is diced and siRNA size (24 or 23 nt).
- Alternative DCL3 dicing patterns diversify siRNA characteristics.
Conclusions:
- A nucleotide-based code governs siRNA production from Pol IV/RDR2 precursors.
- This code optimizes siRNA size, sequence, and strand specificity.
- Diversified siRNAs ensure comprehensive epigenetic silencing of target loci.
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