Genome-wide analysis of SAGA subunits: ada2b, spt3, nonstop, and sgf11, as well as RNA pol II in 1-3 hr embryos of Drosophila melanogaster.

The Spt-Ada-Gcn5-acetyltransferase (SAGA) chromatin-modifying complex is a transcriptional coactivator that contains four different modules of subunits. The intact SAGA complex has been well characterized for its function in transcription regulation and development. However, little is known about the roles of individual modules within SAGA and if they have any SAGA independent functions. Here we demonstrate that the two enzymatic modules of Drosophila SAGA are differently required in oogenesis. Loss of the HAT activity blocks oogenesis, while loss of the DUB activity does not. However, the DUB module regulates a subset of genes in early embryogenesis and loss of the DUB subunits causes defects in embryogenesis. ChIP-seq analysis of ada2b, spt3, nonstop, and sgf11revealed that both the DUB and HAT modules bind most SAGA target genes even though many of these targets do not require the DUB module for expression. Furthermore, we found that the DUB module can bind to chromatin and regulate transcription independently of the rest of SAGA. Our results suggest that the DUB module has functions within SAGA as well as independent functions. Overall design: ChIP Seq analysis of 4 different chromatin modification factors and RNA polymerase II in drosophila embryos was performed with 2 to 4 replicates of each factor.