Nascent Transcript Folding Plays a Major Role in Determining RNA Polymerase Elongation Rates.
Nascent Transcript Folding Plays a Major Role in Determining RNA Polymerase Elongation Rates.
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新生转录本折叠在确定 RNA 聚合酶延伸率中发挥着重要作用。
DOI：
10.1016/j.molcel.2020.06.002
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发表时间：
2020
期刊：
影响因子：
16
通讯作者：
Tollervey,David
中科院分区：
文献类型：
--
作者：
Turowski,TomaszW;Petfalski,Elisabeth;Goddard,BenjaminD;French,SarahL;Helwak,Aleksandra;Tollervey,David
转录延伸率影响RNA加工，但序列特异性调控知之甚少。我们在体内分析了酿酒酵母中的RNAPI。通过米勒染色质扩散或UV交联绘制RNAPI图谱，发现5′富集和沿着rDNA的显著不均匀的局部聚合酶占据，表明转录速度的实质性变化。新生转录本的两个特征与RNAPI分布相关：转录泡中的折叠能和GC含量。体外实验证实，靠近聚合酶的强RNA结构促进正向易位并限制回溯，而转录泡中的高GC减慢延伸。RNAPI延伸的数学模型证实了新生RNA折叠在转录中的重要性。来自粟酒裂殖酵母的RNAPI对转录本折叠同样敏感，而来自粟酒裂殖酵母的RNAPII和RNAPIII也是如此。对于RNAPII，非结构化的RNA，有利于减缓伸长，与更快的共转录剪接和近端剪接位点的使用，表明转录折叠的调节意义。
Transcription elongation rates influence RNA processing, but sequence-specific regulation is poorly understood. We addressed thisin vivo, analyzing RNAPI inS. cerevisiae. Mapping RNAPI by Miller chromatin spreads or UV crosslinking revealed 5′ enrichment and strikingly uneven local polymerase occupancy along the rDNA, indicating substantial variation in transcription speed. Two features of the nascent transcript correlated with RNAPI distribution: folding energy and GC content in the transcription bubble.In vitroexperiments confirmed that strong RNA structures close to the polymerase promote forward translocation and limit backtracking, whereas high GC in the transcription bubble slows elongation. A mathematical model for RNAPI elongation confirmed the importance of nascent RNA folding in transcription. RNAPI fromS. pombewas similarly sensitive to transcript folding, as wereS. cerevisiaeRNAPII and RNAPIII. For RNAPII, unstructured RNA, which favors slowed elongation, was associated with faster cotranscriptional splicing and proximal splice site use, indicating regulatory significance for transcript folding.