Poster abstracts
Poster number 13 submitted by Kristin Chesnutt
Evidence for an acetylation-independent function of the SAGA and ATAC human acetyltransferase modules
Kristin Chesnutt1 (Department of Physics, Ohio State University, Columbus, USA), Gizem Yayli (Institut de Gntique et de Biologie Molculaire et Cellulaire, Illkirch, France), Christine Toelzer (Bristol University, Bristol, UK), Imre Berger (Bristol University, Bristol, UK), Lszl Tora (Institut de Gntique et de Biologie Molculaire et Cellulaire, Illkirch, France), Michael G. Poirier (Department of Physics, Ohio State University, Columbus, USA)
Abstract:
Post translational modifications (PTMs) play a crucial role in transcription regulation by recruiting regulatory complexes and by assisting in the modulation of DNA accessibility to transcription factors (TFs). Human Spt-Ada-Gcn5-acetyltransferase (SAGA) and ADA-two-A-containing (ATAC) are two distinct multifunctional co-activator protein complexes that contain similar histone acetyltransferase (HAT) modules. SAGA and ATAC can be targeted to genomic loci through interactions with histone PTMs and TFs. The mechanism in which SAGA and ATAC function with TFs to target and acetylate nucleosomes remains unknown. Here we used Fluorescence Anisotropy (FA) to characterize human SAGA and ATAC HAT module interactions with nucleosomes. Förster resonance energy transfer (FRET) was used to investigate how SAGA and ATAC HAT modules function with a TF to target nucleosomes. Additionally, Western blot assays were carried out to determine if TFs influence the acetylation activity of SAGA and ATAC HAT modules. We found that the HAT modules of SAGA and ATAC bind with high affinity to nucleosomes, independent of TFs. We also found that the HAT modules can facilitate TF invasion into nucleosomes. Furthermore, interactions with TFs were shown to impact the acetylation activity of the HAT modules. This data is evidence for a new function of SAGA and ATAC HAT modules, displaying an ability to facilitate TF binding to nucleosomes that is acetylation independent.
Keywords: lysine acetylation, transcription regulation, nucleosome