Prior studies suggested that SAGA and TFIID are alternative factors that promote RNA polymerase II transcription, with about 10% of genes in S. cerevisiae dependent on SAGA. We reassessed the role of SAGA by mapping its genome-wide location and role in global transcription in budding yeast. We find that SAGA maps to the UAS elements of most genes, overlapping with Mediator binding and irrespective of previous designations of SAGA- or TFIID-dominated genes. Disruption of SAGA through mutation or rapid subunit depletion reduces transcription from nearly all genes, measured by newly synthesized RNA. We also find that the acetyltransferase Gcn5 synergizes with Spt3 to promote global transcription and that Spt3 functions to stimulate TBP recruitment at all tested genes. Our data demonstrate that SAGA acts as a general cofactor required for essentially all RNA polymerase II transcription and is not consistent with the previous classification of SAGA- and TFIID-dominated genes.

先前的研究表明，SAGA 和 TFIID 是促进 RNA 聚合酶 II 转录的替代因子，在酿酒酵母中约有 10% 的基因依赖于 SAGA。我们通过绘制 SAGA 的全基因组位置和在出芽酵母中的全局转录中的作用，重新评估了 SAGA 的作用。我们发现 SAGA 映射到大多数基因的 UAS 元素，与 Mediator 结合重叠，并且与以前指定的 SAGA 或 TFIID 主导基因无关。通过突变或快速亚基耗竭破坏 SAGA 会减少几乎所有基因的转录，这由新合成的 RNA 测量。我们还发现乙酰转移酶 Gcn5 与 Spt3 协同促进全局转录，并且 Spt3 的作用是刺激所有测试基因的 TBP 募集。我们的数据表明，SAGA 作为基本上所有 RNA 聚合酶 II 转录所需的通用辅助因子，与之前对 SAGA 和 TFIID 主导基因的分类不一致。