6k4n | pdb_00006k4n
Cryo-EM structure of p300
Structural highlights
Disease[EP300_HUMAN] Note=Defects in EP300 may play a role in epithelial cancer. Note=Chromosomal aberrations involving EP300 may be a cause of acute myeloid leukemias. Translocation t(8;22)(p11;q13) with KAT6A. Defects in EP300 are the cause of Rubinstein-Taybi syndrome type 2 (RSTS2) [MIM:613684]. A disorder characterized by craniofacial abnormalities, postnatal growth deficiency, broad thumbs, broad big toes, mental retardation and a propensity for development of malignancies. Some individuals with RSTS2 have less severe mental impairment, more severe microcephaly, and a greater degree of changes in facial bone structure than RSTS1 patients.[1] Function[EP300_HUMAN] Functions as histone acetyltransferase and regulates transcription via chromatin remodeling. Acetylates all four core histones in nucleosomes. Histone acetylation gives an epigenetic tag for transcriptional activation. Mediates cAMP-gene regulation by binding specifically to phosphorylated CREB protein. Also functions as acetyltransferase for nonhistone targets. Acetylates 'Lys-131' of ALX1 and acts as its coactivator in the presence of CREBBP. Acetylates SIRT2 and is proposed to indirectly increase the transcriptional activity of TP53 through acetylation and subsequent attenuation of SIRT2 deacetylase function. Acetylates HDAC1 leading to its inactivation and modulation of transcription. Acts as a TFAP2A-mediated transcriptional coactivator in presence of CITED2. Plays a role as a coactivator of NEUROD1-dependent transcription of the secretin and p21 genes and controls terminal differentiation of cells in the intestinal epithelium. Promotes cardiac myocyte enlargement. Can also mediate transcriptional repression. Binds to and may be involved in the transforming capacity of the adenovirus E1A protein. In case of HIV-1 infection, it is recruited by the viral protein Tat. Regulates Tat's transactivating activity and may help inducing chromatin remodeling of proviral genes. Acetylates FOXO1 and enhances its transcriptional activity.[2] [3] [4] [5] [6] [7] [8] [9] [10] Publication Abstract from PubMedTranscriptional coactivator p300, a critical player in eukaryotic gene regulation, primarily functions as a histone acetyltransferase (HAT). It is also an important player in acetylation of a number of non-histone proteins, p53 being the most prominent one. Recruitment of p300 to p53 is pivotal in the regulation of p53-dependent genes. Emerging evidence suggest that p300 adopts an active conformation upon binding to the tetrameric p53, resulting in its enhanced acetylation activity. As a modular protein, p300 consists of multiple well-defined domains where the structured domains are interlinked with unstructured linker regions. A crystal structure of the central domain of p300 encompassing Bromo, RING, PHD and histone acetyltransferases (HAT) domains demonstrates a compact module where the HAT active site stays occluded by the RING domain. However, although p300 has a significant role in mediating the transcriptional activity of p53, little structural details on the complex of these two full-length proteins are available. Here, we present a cryo-electron microscopy (cryo-EM) study on the p300-p53 complex. The 3D cryo-EM density map of the p300-p53 complex, when compared to the cryo-EM map of free p300, revealed that substantial change in the relative arrangement of Bromo and HAT domains occurs upon complex formation which is likely required for exposing HAT active site and subsequent acetyltransferases activity. Our observation correlates well with previous studies showing that the presence of Bromodomain is obligatory for effective acetyltransferase activity of HAT. Thus, our result sheds new light on the mechanism whereby p300, following binding with p53, gets activated. Tumor suppressor p53-mediated structural reorganization of the transcriptional coactivator p300.,Ghosh R, Kaypee S, Shasmal M, Kundu TK, Roy S, Sengupta J Biochemistry. 2019 Jul 17. doi: 10.1021/acs.biochem.9b00333. PMID:31314496[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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