The Essential Gene wda Encodes a WD40 Repeat Subunit of Drosophila SAGA Required for Histone H3 Acetylation

Abstract

Histone acetylation provides a switch between transcriptionally repressive and permissive chromatin. By regulating the chromatin structure at specific promoters, histone acetyltransferases (HATs) carry out important functions during differentiation and development of higher eukaryotes. HAT complexes are present in organisms as diverse as Saccharomyces cerevisiae, humans, and flies. For example, the well-studied yeast SAGA is related to three mammalian complexes. We previously identified Drosophila melanogaster orthologues of yeast SAGA components Ada2, Ada3, Spt3, and Tra1 and demonstrated that they associate with dGcn5 in a high-molecular-weight complex. To better understand the function of Drosophila SAGA (dSAGA), we sought to affinity purify and characterize this complex in more detail. A proteomic approach led to the identification of an orthologue of the yeast protein Ada1 and the novel protein encoded by CG4448, referred to as WDA (will decrease acetylation). Embryos lacking both alleles of the wda gene exhibited reduced levels of histone H3 acetylation and could not develop into adult flies. Our results point to a critical function of dSAGA and histone acetylation during Drosophila development.

We thank members of the Workman and Abmayr labs for helpful discussions and technical advice. We also thank Jeff Haug and Joshua Wunderlich for the EGFP sorting of Drosophila embryos and Danny Stark and Kiran Kocherlakota for help with confocal microscopy. We thank Joanna Wysocka and David Allis for providing the H3 peptides for the pull-down experiments.