Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
Cell Rep. 2021 Sep 28;36(13):109755. doi: 10.1016/j.celrep.2021.109755.
Spt4 is a transcription elongation factor with homologs in organisms with nucleosomes. Structural and in vitro studies implicate Spt4 in transcription through nucleosomes, and yet the in vivo function of Spt4 is unclear. Here, we assess the precise position of Spt4 during transcription and the consequences of the loss of Spt4 on RNA polymerase II (RNAPII) dynamics and nucleosome positioning in Saccharomyces cerevisiae. In the absence of Spt4, the spacing between gene-body nucleosomes increases and RNAPII accumulates upstream of the nucleosomal dyad, most dramatically at nucleosome +2. Spt4 associates with elongating RNAPII early in transcription, and its association dynamically changes depending on nucleosome positions. Together, our data show that Spt4 regulates early elongation dynamics, participates in co-transcriptional nucleosome positioning, and promotes RNAPII movement through the gene-body nucleosomes, especially the +2 nucleosome.
Spt4 是一种转录延伸因子，在具有核小体的生物中具有同源物。结构和体外研究表明 Spt4 通过核小体参与转录，但 Spt4 的体内功能尚不清楚。在这里，我们评估了 Spt4 在转录过程中的精确位置，以及 Spt4 缺失对 RNA 聚合酶 II（RNAPII）动力学和核小体在酿酒酵母中定位的影响。在没有 Spt4 的情况下，基因体核小体之间的间隔增加，RNAPII 在核小体二联体的上游积累，在核小体+2 处最为明显。Spt4 在转录早期与延伸中的 RNAPII 结合，其结合动态取决于核小体位置。总之，我们的数据表明 Spt4 调节早期延伸动力学，参与共转录核小体定位，并促进 RNAPII 通过基因体核小体运动，特别是+2 核小体。
