小柯机器人

南方科技大学杜嘉木研究组报道植物RNA聚合酶V的结构与机制。这一研究成果于2023年3月9日在线发表在国际学术期刊《科学》上。

研究人员表示，除了真核生物中保守的RNA聚合酶（Pol）I-III，两个非典型的聚合酶，Pols IV和V，在植物中的RNA指导的DNA甲基化（RdDM）途径中专门产生非编码RNA。

研究人员报告了花椰菜Pol V在自由和延伸构象中的结构。NRPE2的一个保守的酪氨酸残基与转录泡的dsDNA分支堆叠在一起，可能通过诱导转录停滞而减弱延伸。非模板DNA链被NRPE2捕获以加强回溯，从而增加3′-5′切割，这可能是Pol V的高保真度的基础。这些结构还阐明了Pol V转录停滞和加强回溯的机制，这可能对Pol V保留在染色质上以发挥其拴住下游因子进行RdDM的功能很重要。

附：英文原文

Title: Structure and mechanism of the plant RNA polymerase V

Author: Guohui Xie, Xuan Du, Hongmiao Hu, Sisi Li, Xiaofeng Cao, Steven E. Jacobsen, Jiamu Du

Issue&Volume: 2023-03-09

Abstract: In addition to the conserved RNA polymerases (Pols) I-III in eukaryotes, two atypical polymerases, Pols IV and V, specifically produce non-coding RNA in the RNA-directed DNA methylation (RdDM) 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 dsDNA branch of the transcription bubble to potentially attenuate elongation by inducing transcription stalling. The non-template 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 RdDM.

DOI: adf8231

Source: https://www.science.org/doi/10.1126/science.adf8231