Structure and mechanism of the plant RNA polymerase V

• 成果类型: Article
• 署名作者: Xie, Guohui; Du, Xuan; Hu, Hongmiao; Li, Sisi; Cao, Xiaofeng; Jacobsen, Steven E.; Du, Jiamu
• 署名单位: Southern University of Science & Technology; Shenzhen University; Chinese Academy of Sciences; Institute of Genetics & Developmental Biology, CAS; University of California System; University of California Los Angeles; University of California System; University of California Los Angeles; Howard Hughes Medical Institute
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-10078
• DOI: 10.1126/science.adf8231
• 发表日期: 2023-03-24
• 页码: 1209-1213
• 关键词: directed dna methylation; pol iv; transcription; argonaute4; drm; subunits; enzymes; reveal; FAMILY; forms

摘要

In addition to the conserved RNA polymerases Ito III (Pols Ito III) in eukaryotes, two atypical polymerases, Pols IV and V, specifically produce noncoding RNA in the RNA-directed DNA methylation pathway in plants. Here, we report on the structures of cauliflower Pol V in the free and elongation conformations. A conserved tyrosine residue of NRPE2 stacks with a double -stranded DNA branch of the transcription bubble to potentially attenuate elongation by inducing transcription stalling. The nontemplate DNA strand is captured by NRPE2 to enhance backtracking, thereby increasing 3 '-5 ' cleavage, which likely underpins Pol V's high fidelity. The structures also illuminate the mechanism of Pol V transcription stalling and enhanced backtracking, which may be important for Pol V's retention on chromatin to serve its function in tethering downstream factors for RNA-directed DNA methylation.