Poster abstracts
Poster number 61 submitted by Kristin Chesnutt
ATAC and SAGA histone acetyltransferase modules facilitate transcription factor binding to nucleosomes in an acetylation independent manner
Kristin Chesnutt (Ohio State Biochemistry Program), Gizem Yayli (Institut de Genetique et de Biologie Moleculaire et Cellulaire), Christine Toelzer (Bristol University), Khan Cox (OSU Department of Physics), Laszlo Tora (Institut de Genetique et de Biologie Moleculaire et Cellulaire), Michael G. Poirier (OSU Department of Physics)
Abstract:
Transcriptional control by RNA polymerase II (Pol II) involves the cooperation of chromatin regulatory complexes, which remodel and/or modify nucleosomes. Chromatin modifying complexes can deposit, bind, and remove post-translational modifications (PTMs) of histones. Transcriptional coactivator complexes, ATAC (ADA-Two-A-Containing) and SAGA (Spt-Ada-Gcn5-acetyltransferase), acetylate histones at distinct residues and can be targeted to genomic loci through interactions with transcription factors. To better understand the function of ATAC and SAGA histone acetyltransferase (HAT) complexes we used in vitro Fluorescence Anisotropy to characterize human ATAC and SAGA HAT interactions with nucleosomes. We found that ATAC and SAGA bind with high affinity to nucleosomes, independent of post translational modifications (PTMs) and transcription factors (TFs). Additionally, we investigated the mechanism in which ATAC and SAGA HAT modules function with a TF to target and acetylate nucleosomes using Förster resonance energy transfer (FRET). Both ATAC and SAGA can facilitate TF invasion into nucleosomes independent of acetylation. Furthermore, acetylation assays revealed TFs impact acetylation activity of the HAT modules. Altogether, our results show evidence for a new function of the ATAC and SAGA HAT modules, displaying an ability to facilitate TF binding to nucleosomes that is acetylation independent.
Keywords: lysine acetylation, transcription regulation, nucleosome dynamics