Spt6 is a conserved factor that controls transcription and chromatin structure across the genome. Although Spt6 is viewed as an elongation factor, spt6 mutations in Saccharomyces cerevisiae allow elevated levels of transcripts from within coding regions, suggesting that Spt6 also controls initiation. To address the requirements for Spt6 in transcription and chromatin structure, we have combined four genome-wide approaches. Our results demonstrate that Spt6 represses transcription initiation at thousands of intragenic promoters. We characterize these intragenic promoters and find sequence features conserved with genic promoters. Finally, we show that Spt6 also regulates transcription initiation at most genic promoters and propose a model of initiation site competition to account for this. Together, our results demonstrate that Spt6 controls the fidelity of transcription initiation throughout the genome.

Spt6是一种保守因子，可控制整个基因组中的转录和染色质结构。尽管Spt6被视为一种延伸因子，但酿酒酵母中的spt6突变允许来自编码区域内的转录物水平升高，表明Spt6也控制起始。为了解决Spt6在转录和染色质结构方面的要求，我们结合了四种全基因组方法。我们的结果表明，Spt6抑制数千种基因内启动子的转录起始。我们表征这些基因内启动子，并找到与基因启动子保守的序列特征。最后，我们证明了Spt6还调节大多数基因启动子的转录起始，并提出了起始位点竞争的模型来解释这一点。在一起，我们的结果表明，Spt6控制整个基因组中转录起始的保真度。