RNA聚合酶Ⅱ
抄写(语言学)
生物
发起人
转录因子ⅡD
一般转录因子
细胞生物学
解旋酶
转录前起始复合物
RNA聚合酶
转录泡
上游激活序列
分子生物学
基因
遗传学
核糖核酸
基因表达
哲学
语言学
作者
Clemens Grimm,J. Bartuli,Bettina Boettcher,Aladar A. Szalay,Utz Fischer
标识
DOI:10.1038/s41594-021-00655-w
摘要
Poxviruses express their genes in the cytoplasm of infected cells using a virus-encoded multi-subunit polymerase (vRNAP) and unique transcription factors. We present cryo-EM structures that uncover the complete transcription initiation phase of the poxvirus vaccinia. In the pre-initiation complex, the heterodimeric early transcription factor VETFs/l adopts an arc-like shape spanning the polymerase cleft and anchoring upstream and downstream promoter elements. VETFI emerges as a TBP-like protein that inserts asymmetrically into the DNA major groove, triggers DNA melting, ensures promoter recognition and enforces transcription directionality. The helicase VETFs fosters promoter melting and the phospho-peptide domain (PPD) of vRNAP subunit Rpo30 enables transcription initiation. An unprecedented upstream promoter scrunching mechanism assisted by the helicase NPH-I probably fosters promoter escape and transition into elongation. Our structures shed light on unique mechanisms of poxviral gene expression and aid the understanding of thus far unexplained universal principles in transcription.
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