Gcn4 binding in coding regions can activate internal and canonical 5' promoters in yeast [RNA-seq]

Gcn4 is a yeast transcriptional activator induced by amino acid starvation. ChIP-seq analysis revealed 546 genomic sites occupied by Gcn4 in starved cells, representing ~30% of all Gcn4 binding-motifs. Deviation from the consensus motif and nucleosome occupancy are key negative determinants of Gcn4 binding. Surprisingly, only ~40% of the bound sites are in promoter regions, and only ~50-67% of these activate transcription, indicating extensive negative control over Gcn4 function. Most of the remaining ~300 Gcn4-bound sites are within coding sequences (CDS), with ~75 representing the only bound sites near Gcn4-induced genes. Many such unconventional sites map between divergent antisense and sub-genic sense transcripts induced within CDS, adjacent to induced TBP peaks—consistent with Gcn4 activation of cryptic, bidirectional internal promoters. Mutational analysis confirms that Gcn4 sites within CDS can activate sub-genic and full-length transcripts from the same or adjacent genes, showing that functional Gcn4 binding is not confined to promoters. Overall design: We analyzed the transcriptome in wild type yeast cells after induction by 3-AT and SM by RNA-seq. The ChIP-seq data is GSE107532.

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Rawal Y, Chereji RV, Valabhoju V, Qiu H, Ocampo J, Clark DJ, Hinnebusch AG