Structural insights into p300 regulation and acetylation-dependent genome organisation

Abstract

Histone modifications are deposited by chromatin modifying enzymes and read out by proteins that recognize the modified state. BRD4-NUT is an oncogenic fusion protein of the acetyl lysine reader BRD4 that binds to the acetylase p300 and enables formation of large hyperacetylated chromatin megadomains. We here examine how reading and writing contribute to larger-scale chromatin architecture. We show that NUT contains an acidic transcriptional activation domain that binds to the TAZ2 domain of p300. We use NMR to investigate the structure of the complex and found that the TAZ2 domain has an autoinhibitory role for p300. NUT-TAZ2 interaction or mutants that interfere with autoinhibition by TAZ2 allosterically activate p300. p300 activation results in a self-organizing, acetylation-dependent feed-forward reaction that enables large-scale intra- and interchromosomal interactions by bromodomain multivalent acetyl-lysine binding. We discuss how the acetylation-dependent read-write reaction drives condensation and the implications for chromatin organisation, gene regulation and dysregulation in disease.

Case report: Immunovirotherapy as a novel add-on treatment in a patient with thoracic NUT carcinoma

“…It plays a major role in recruiting transcriptional regulators such as NSD1-3 and JMJD6 ( 30 ). Our findings suggest that the protein recruiting ET is not essential for the oncogenic function of the NUT fusion protein and supports recent in vitro studies suggesting that the two bromodomains of BRD4 in a fusion protein with NUT are sufficient for the formation of the pathological hyperacetylated megadomains ( 31 ). However, a fully intact wild-type BRD4 protein seems to be crucial for the formation of the oncogenic nuclear complex and the pathogenesis of non-BRD4-NUT fusion NC ( 32 – 34 ).…”

Menke-Hennekam syndrome; delineation of domain-specific subtypes with distinct clinical and DNA methylation profiles

“…Ibrahim et al. 38 proposed that the first α helix of ID4 (in addition to the TAZ2 domain) of p300 plays a role in allosteric HAT regulation by displacement of the TAZ2 domain from its auto-inhibitory position, resulting in HAT activation, also indicating a possible gain of function. Our AlphaFold figures of CBP and p300 predict a close spatial proximity between the ID4 helix and HAT domain, as well as multiple hydrogen bonds between residues from each domain/region.…”

EZH2 synergizes with BRD4-NUT to drive NUT carcinoma growth through silencing of key tumor suppressor genes

“…BRD4-NUT also reprograms chromatin 3D structure resulting in inter-chromosomal DNA interactions between these lineage-defining transcription factors 10,11 . Megadomains and chromatin 3D interactions mediated by BRD4-NUT can be visualized immunohistochemically by light microscopy or by immunofluorescence microscopy 8,[12][13][14] . The functional outcome of these BRD4-NUT-driven processes is blockade of differentiation and maintenance of growth of NC cells.…”