The SAGA coactivator regulates the expression of nearly all genes transcribed by RNA polymerase II

The SAGA coactivator complex facilitates transcription initiation through chromatin-modifying activities and interaction with TBP. SAGA was suggested to regulate the expression of about 10% of yeast genes, leading to the longstanding distinction of SAGA-dominated from TFIID-dominated genes, depending on the complex used to recruit TBP to promoters. We reassessed the genome-wide localization of SAGA by using ChEC-seq and its role on transcription through quantification of newly-synthesized mRNA. Here we show that SAGA binds to the upstream activating sequences of a majority of yeast genes. Deletion analyses reveal a global role for SAGA in transcription and a synergistic effect of Spt3 (TBP-binding subunit) with the acetyltransferase Gcn5. Our data demonstrate that SAGA acts as a general cofactor required for essentially all RNA polymerase II transcription. Hence, differential gene regulation, largely attributed to either SAGA or TFIID dominancy, is not accurate, but instead depends on other features of genes promoters. We used ChEC-seq to map the genome-wide binding of the SAGA coactivator complex in budding yeast. ChEC-seq was performed as described in PMID 27797823.