The structural basis of protein acetylation by the p300/CBP transcriptional coactivator

Abstract

The transcriptional coactivator p300/CBP (CREBBP) is a histone acetyltransferase (HAT) that regulates gene expression by acetylating histones and other transcription factors. Dysregulation of p300/CBP HAT activity contributes to various diseases including cancer. Sequence alignments, enzymology experiments and inhibitor studies on p300/CBP have led to contradictory results about its catalytic mechanism and its structural relation to the Gcn5/PCAF and MYST HATs. Here we describe a high-resolution X-ray crystal structure of a semi-synthetic heterodimeric p300 HAT domain in complex with a bi-substrate inhibitor, Lys-CoA. This structure shows that p300/CBP is a distant cousin of other structurally characterized HATs, but reveals several novel features that explain the broad substrate specificity and preference for nearby basic residues. Based on this structure and accompanying biochemical data, we propose that p300/CBP uses an unusual 'hit-and-run' (Theorell-Chance) catalytic mechanism that is distinct from other characterized HATs. Several disease-associated mutations can also be readily accounted for by the p300 HAT structure. These studies pave the way for new epigenetic therapies involving modulation of p300/CBP HAT activity.

A constitutional variant in the transcription factor EP300 strongly influences the clinical outcome of patients submitted to allo-SCT

“…EP300 has a critical role in biological process involved in tumorigenesis. 17,21 Thus, gene mutations that modify the structure of EP300 appear in several types of cancer. 21 --23 EP300 and CBP (CREB-binding protein) give rise to the transcriptional coactivator P300/CBP.…”

“…26 EP300 also has a critical role in the Influence of EP300 variant on allo-SCT outcome B Martín-Antonio et al inflammatory response. 17,21 Thus, following viral infection, IRF-3 associates with P300/CBP and translocates to the nucleus to induce IFN-b transcription. 17,27 All these important biological effects mediated by EP300 might explain why a constitutional variant in this gene influences the clinical outcome after allo-SCT.…”

Structural and Functional Role of Acetyltransferase hMOF K274 Autoacetylation

“…Briefly, 50 nM hMOF or 200 nM MOZ was incubated with 400 M substrate peptide (H4(1-19) peptide for hMOF and H3 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) for MOZ) (GenScript) and 50 M […”

An old HAT in human p300/CBP and yeast Rtt109

“…2 Two key departures from the core GNAT/MYST HAT fold-a long unstructured chain (or "flap") overlaying the acetyl-CoA (AcCoA) binding groove, and a four-a-helix "tower" excursion from the main b-sheet-critically contribute to the recognition and presumptive catalytic machinery of p300/CBP HAT enzymes. Kinetic and mutant analysis of this enlarged residue constellation in p300 (which is distinct from functional fingerprints drawn from GNAT or MYST complexes 2 ) led Liu et al, 1 to suggest that p300/CBP works with an unorthodox "hit and run" mechanism that enlists Tyr1467 as the critical catalytic residue. In order to extend the evolutionary testbed for this variant HAT mechanism beyond the thin roll of p300/ CBP orthologs, I propose that Rtt109, a novel yeast HAT that has so far eluded classification, is the prototype of a fungal clan of p300-related enzymes that preserve the embellished HAT fold, but further diversify its catalytic options.…”

“…1A), the Rtt109 HAT model is largely complete and compels a closer inspection of residues lining the p300-derived LysCoA binding groove, catalytic site and peptide-recognition pockets. 1 While the binding groove walls in Rtt109 retain a very conserved character (Fig. 2), the catalytic site shows some small but intriguing differences from p300.…”