RNA-directed DNA methylation involves co-transcriptional small-RNA-guided slicing of polymerase V transcripts in Arabidopsis
| Autor: | Jonathan Hetzel, Zonghua Wang, Suhua Feng, Hsuan Yu Kuo, Steven E. Jacobsen, Zhenhui Zhong, Jixian Zhai, Javier Gallego-Bartolomé, Sascha H. Duttke, Wanlu Liu, Martin Groth, Joanne Chory |
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| Rok vydání: | 2017 |
| Předmět: |
0106 biological sciences
0301 basic medicine Small RNA Transcription Genetic Arabidopsis Plant Science 01 natural sciences Article 03 medical and health sciences Transcription (biology) RNA Small Nuclear Gene Silencing RNA-Directed DNA Methylation RNA polymerase V Chemistry Arabidopsis Proteins RNA DNA-Directed RNA Polymerases Argonaute DNA Methylation Chromatin Cell biology 030104 developmental biology DNA methylation Argonaute Proteins 010606 plant biology & botany Genome-Wide Association Study RNA Guide Kinetoplastida |
| Zdroj: | Nature plants |
| ISSN: | 2055-0278 |
| Popis: | Small RNAs regulate chromatin modifications such as DNA methylation and gene silencing across eukaryotic genomes. In plants, RNA-directed DNA methylation (RdDM) requires 24-nucleotide small interfering RNAs (siRNAs) that bind to ARGONAUTE 4 (AGO4) and target genomic regions for silencing. RdDM also requires non-coding RNAs transcribed by RNA polymerase V (Pol V) that probably serve as scaffolds for binding of AGO4-siRNA complexes. Here, we used a modified global nuclear run-on protocol followed by deep sequencing to capture Pol V nascent transcripts genome-wide. We uncovered unique characteristics of Pol V RNAs, including a uracil (U) common at position 10. This uracil was complementary to the 5' adenine found in many AGO4-bound 24-nucleotide siRNAs and was eliminated in a siRNA-deficient mutant as well as in the ago4/6/9 triple mutant, suggesting that the +10 U signature is due to siRNA-mediated co-transcriptional slicing of Pol V transcripts. Expression of wild-type AGO4 in ago4/6/9 mutants was able to restore slicing of Pol V transcripts, but a catalytically inactive AGO4 mutant did not correct the slicing defect. We also found that Pol V transcript slicing required SUPPRESSOR OF TY INSERTION 5-LIKE (SPT5L), an elongation factor whose function is not well understood. These results highlight the importance of Pol V transcript slicing in RNA-mediated transcriptional gene silencing, which is a conserved process in many eukaryotes. |
| Databáze: | OpenAIRE |
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