A DCL3 dicing code within Pol IV-RDR2 transcripts diversifies the siRNA pool guiding RNA-directed DNA methylation.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35098919.
- Also identified by DOI 10.7554/eLife.73260 and PMC identifier 8846587.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
In plants, selfish genetic elements, including retrotransposons and DNA viruses, are transcriptionally silenced by RNA-directed DNA methylation. Guiding the process are short interfering RNAs (siRNAs) cut by DICER-LIKE 3 (DCL3) from double-stranded precursors of ~30 bp that are synthesized by NUCLEAR RNA POLYMERASE IV (Pol IV) and RNA-DEPENDENT RNA POLYMERASE 2 (RDR2). We show that Pol IV's choice of initiating nucleotide, RDR2's initiation 1-2 nt internal to Pol IV transcript ends and RDR2's terminal transferase activity collectively yield a code that influences which precursor end is diced and whether 24 or 23 nt siRNAs are produced. By diversifying the size, sequence, and strand specificity of siRNAs derived from a given precursor, alternative patterns of DCL3 dicing allow for maximal siRNA coverage at methylated target loci.
Medical subject headings
- Arabidopsis
- Arabidopsis Proteins
- Gene Expression Regulation, Plant
- RNA, Small Interfering
- Ribonuclease III
- Transcription, Genetic