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==Human p53 core domain with hot spot mutation R273C and second-site suppressor mutation T284R in sequence-specific complex with DNA==
<StructureSection load='4ibu' size='340' side='right'caption='[[4ibu]], [[Resolution|resolution]] 1.70&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4ibu]] is a 8 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4IBU OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4IBU FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.7&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene>, <scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4ibu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4ibu OCA], [https://pdbe.org/4ibu PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4ibu RCSB], [https://www.ebi.ac.uk/pdbsum/4ibu PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4ibu ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/P53_HUMAN P53_HUMAN] Note=TP53 is found in increased amounts in a wide variety of transformed cells. TP53 is frequently mutated or inactivated in about 60% of cancers. TP53 defects are found in Barrett metaplasia a condition in which the normally stratified squamous epithelium of the lower esophagus is replaced by a metaplastic columnar epithelium. The condition develops as a complication in approximately 10% of patients with chronic gastroesophageal reflux disease and predisposes to the development of esophageal adenocarcinoma.  Defects in TP53 are a cause of esophageal cancer (ESCR) [MIM:[https://omim.org/entry/133239 133239].  Defects in TP53 are a cause of Li-Fraumeni syndrome (LFS) [MIM:[https://omim.org/entry/151623 151623]. LFS is an autosomal dominant familial cancer syndrome that in its classic form is defined by the existence of a proband affected by a sarcoma before 45 years with a first degree relative affected by any tumor before 45 years and another first degree relative with any tumor before 45 years or a sarcoma at any age. Other clinical definitions for LFS have been proposed (PubMed:8118819 and PubMed:8718514) and called Li-Fraumeni like syndrome (LFL). In these families affected relatives develop a diverse set of malignancies at unusually early ages. Four types of cancers account for 80% of tumors occurring in TP53 germline mutation carriers: breast cancers, soft tissue and bone sarcomas, brain tumors (astrocytomas) and adrenocortical carcinomas. Less frequent tumors include choroid plexus carcinoma or papilloma before the age of 15, rhabdomyosarcoma before the age of 5, leukemia, Wilms tumor, malignant phyllodes tumor, colorectal and gastric cancers.<ref>PMID:10570149</ref> <ref>PMID:1933902</ref> <ref>PMID:1978757</ref> <ref>PMID:2259385</ref> <ref>PMID:1737852</ref> <ref>PMID:1565144</ref> <ref>PMID:7887414</ref> <ref>PMID:8825920</ref> <ref>PMID:9452042</ref> <ref>PMID:10484981</ref>   Defects in TP53 are involved in head and neck squamous cell carcinomas (HNSCC) [MIM:[https://omim.org/entry/275355 275355]; also known as squamous cell carcinoma of the head and neck.  Defects in TP53 are a cause of lung cancer (LNCR) [MIM:[https://omim.org/entry/211980 211980]. LNCR is a common malignancy affecting tissues of the lung. The most common form of lung cancer is non-small cell lung cancer (NSCLC) that can be divided into 3 major histologic subtypes: squamous cell carcinoma, adenocarcinoma, and large cell lung cancer. NSCLC is often diagnosed at an advanced stage and has a poor prognosis.  Defects in TP53 are a cause of choroid plexus papilloma (CPLPA) [MIM:[https://omim.org/entry/260500 260500]. Choroid plexus papilloma is a slow-growing benign tumor of the choroid plexus that often invades the leptomeninges. In children it is usually in a lateral ventricle but in adults it is more often in the fourth ventricle. Hydrocephalus is common, either from obstruction or from tumor secretion of cerebrospinal fluid. If it undergoes malignant transformation it is called a choroid plexus carcinoma. Primary choroid plexus tumors are rare and usually occur in early childhood.<ref>PMID:12085209</ref>   Defects in TP53 are a cause of adrenocortical carcinoma (ADCC) [MIM:[https://omim.org/entry/202300 202300]. ADCC is a rare childhood tumor of the adrenal cortex. It occurs with increased frequency in patients with the Beckwith-Wiedemann syndrome and is a component tumor in Li-Fraumeni syndrome.<ref>PMID:11481490</ref>   Defects in TP53 are the cause of susceptibility to basal cell carcinoma 7 (BCC7) [MIM:[https://omim.org/entry/614740 614740]. A common malignant skin neoplasm that typically appears on hair-bearing skin, most commonly on sun-exposed areas. It is slow growing and rarely metastasizes, but has potentialities for local invasion and destruction. It usually develops as a flat, firm, pale area that is small, raised, pink or red, translucent, shiny, and waxy, and the area may bleed following minor injury. Tumor size can vary from a few millimeters to several centimeters in diameter.<ref>PMID:21946351</ref> 
== Function ==
[https://www.uniprot.org/uniprot/P53_HUMAN P53_HUMAN] Acts as a tumor suppressor in many tumor types; induces growth arrest or apoptosis depending on the physiological circumstances and cell type. Involved in cell cycle regulation as a trans-activator that acts to negatively regulate cell division by controlling a set of genes required for this process. One of the activated genes is an inhibitor of cyclin-dependent kinases. Apoptosis induction seems to be mediated either by stimulation of BAX and FAS antigen expression, or by repression of Bcl-2 expression. In cooperation with mitochondrial PPIF is involved in activating oxidative stress-induced necrosis; te function is largely independent of transcription. Induces the transcription of long intergenic non-coding RNA p21 (lincRNA-p21) and lincRNA-Mkln1. LincRNA-p21 participates in TP53-dependent transcriptional repression leading to apoptosis and seem to have to effect on cell-cycle regulation. Implicated in Notch signaling cross-over. Prevents CDK7 kinase activity when associated to CAK complex in response to DNA damage, thus stopping cell cycle progression. Isoform 2 enhances the transactivation activity of isoform 1 from some but not all TP53-inducible promoters. Isoform 4 suppresses transactivation activity and impairs growth suppression mediated by isoform 1. Isoform 7 inhibits isoform 1-mediated apoptosis.<ref>PMID:9840937</ref> <ref>PMID:11025664</ref> <ref>PMID:12810724</ref> <ref>PMID:15186775</ref> <ref>PMID:15340061</ref> <ref>PMID:17317671</ref> <ref>PMID:17349958</ref> <ref>PMID:19556538</ref> <ref>PMID:20673990</ref> <ref>PMID:20959462</ref> <ref>PMID:22726440</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
A p53 hot-spot mutation found frequently in human cancer is the replacement of R273 by histidine or cysteine residues resulting in p53 loss of function as a tumor suppressor. These mutants can be reactivated by the incorporation of second-site suppressor mutations. Here, we present high-resolution crystal structures of the p53 core domains of the cancer-related proteins, the rescued proteins and their complexes with DNA. The structures show that inactivation of p53 results from the incapacity of the mutated residues to form stabilizing interactions with the DNA backbone, and that reactivation is achieved through alternative interactions formed by the suppressor mutations. Detailed structural and computational analysis demonstrates that the rescued p53 complexes are not fully restored in terms of DNA structure and its interface with p53. Contrary to our previously studied wild-type (wt) p53-DNA complexes showing non-canonical Hoogsteen A/T base pairs of the DNA helix that lead to local minor-groove narrowing and enhanced electrostatic interactions with p53, the current structures display Watson-Crick base pairs associated with direct or water-mediated hydrogen bonds with p53 at the minor groove. These findings highlight the pivotal role played by R273 residues in supporting the unique geometry of the DNA target and its sequence-specific complex with p53.

Structural studies of p53 inactivation by DNA-contact mutations and its rescue by suppressor mutations via alternative protein-DNA interactions.,Eldar A, Rozenberg H, Diskin-Posner Y, Rohs R, Shakked Z Nucleic Acids Res. 2013 Jul 17. PMID:23863845<ref>PMID:23863845</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4ibu" style="background-color:#fffaf0;"></div>

==See Also==
*[[P53 3D structures|P53 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Diskin-Posner Y]]
[[Category: Eldar A]]
[[Category: Rozenberg H]]
[[Category: Shakked Z]]