The tumor suppressor functions of p53 and its roles in regulating the cell cycle, apoptosis, senescence, and metabolism are accomplished mainly by its interactions with DNA. p53 works as a transcription factor for a significant number of genes. Most p53 target genes contain so-called p53 response elements in their promoters, consisting of 20 bp long canonical consensus sequences. Compared to other transcription factors, which usually bind to one concrete and clearly defined DNA target, the p53 consensus sequence is not strict, but contains two repeats of a 5'RRRCWWGYYY3' sequence; therefore it varies remarkably among target genes. Moreover, p53 binds also to DNA fragments that at least partially and often completely lack this consensus sequence. p53 also binds with high affinity to a variety of non-B DNA structures including Holliday junctions, cruciform structures, quadruplex DNA, triplex DNA, DNA loops, bulged DNA, and hemicatenane DNA. In this review, we summarize information of the interactions of p53 with various DNA targets and discuss the functional consequences of the rich world of p53 DNA binding targets for its complex regulatory functions.

• Klíčová slova
• consensus sequence, cruciform, local DNA structures, p53, protein-DNA interactions,
• MeSH
• DNA chemie   metabolismus   MeSH
• konformace nukleové kyseliny MeSH
• konformace proteinů MeSH
• konsenzuální sekvence MeSH
• lidé MeSH
• molekulární modely MeSH
• nádorový supresorový protein p53 chemie   metabolismus   MeSH
• sekvence aminokyselin MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• DNA MeSH
• nádorový supresorový protein p53 MeSH

Expansions of trinucleotide repeats (TNRs) are associated with genetic disorders such as Friedreich's ataxia. The tumor suppressor p53 is a central regulator of cell fate in response to different types of insults. Sequence and structure-selective modes of DNA recognition are among the main attributes of p53 protein. The focus of this work was analysis of the p53 structure-selective recognition of TNRs associated with human neurodegenerative diseases. Here, we studied binding of full length p53 and several deletion variants to TNRs folded into DNA hairpins or loops. We demonstrate that p53 binds to all studied non-B DNA structures, with a preference for non-B DNA structures formed by pyrimidine (Py) rich strands. Using deletion mutants, we determined the C-terminal DNA binding domain of p53 to be crucial for recognition of such non-B DNA structures. We also observed that p53 in vitro prefers binding to the Py-rich strand over the purine (Pu) rich strand in non-B DNA substrates formed by sequence derived from the first intron of the frataxin gene. The binding of p53 to this region was confirmed using chromatin immunoprecipitation in human Friedreich's ataxia fibroblast and adenocarcinoma cells. Altogether these observations provide further evidence that p53 binds to TNRs' non-B DNA structures.

• Klíčová slova
• DNA hairpin, DNA–protein, frataxin, non-B DNA, p53, trinucleotide repeat,
• MeSH
• DNA chemie   metabolismus   MeSH
• expanze trinukleotidových repetic * MeSH
• exprese genu MeSH
• Friedreichova ataxie genetika   metabolismus   MeSH
• interakční proteinové domény a motivy MeSH
• konformace nukleové kyseliny * MeSH
• lidé MeSH
• nádorový supresorový protein p53 chemie   metabolismus   MeSH
• pyrimidiny MeSH
• rekombinantní proteiny MeSH
• trinukleotidové repetice * MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA MeSH
• nádorový supresorový protein p53 MeSH
• pyrimidiny MeSH
• rekombinantní proteiny MeSH
• TP53 protein, human MeSH Prohlížeč

p53 plays critical roles in regulating cell cycle, apoptosis, senescence and metabolism and is commonly mutated in human cancer. These roles are achieved by interaction with other proteins, but particularly by interaction with DNA. As a transcription factor, p53 is well known to bind consensus target sequences in linear B-DNA. Recent findings indicate that p53 binds with higher affinity to target sequences that form cruciform DNA structure. Moreover, p53 binds very tightly to non-B DNA structures and local DNA structures are increasingly recognized to influence the activity of wild-type and mutant p53. Apart from cruciform structures, p53 binds to quadruplex DNA, triplex DNA, DNA loops, bulged DNA and hemicatenane DNA. In this review, we describe local DNA structures and summarize information about interactions of p53 with these structural DNA motifs. These recent data provide important insights into the complexity of the p53 pathway and the functional consequences of wild-type and mutant p53 activation in normal and tumor cells.

• Klíčová slova
• local DNA structures, p53 protein, protein-DNA interactions,
• MeSH
• B-DNA MeSH
• DNA chemie   genetika   metabolismus   MeSH
• konformace nukleové kyseliny * MeSH
• lidé MeSH
• nádorový supresorový protein p53 chemie   metabolismus   MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• B-DNA MeSH
• DNA MeSH
• nádorový supresorový protein p53 MeSH
• triplex DNA MeSH Prohlížeč

Triplex DNA is implicated in a wide range of biological activities, including regulation of gene expression and genomic instability leading to cancer. The tumor suppressor p53 is a central regulator of cell fate in response to different type of insults. Sequence and structure specific modes of DNA recognition are core attributes of the p53 protein. The focus of this work is the structure-specific binding of p53 to DNA containing triplex-forming sequences in vitro and in cells and the effect on p53-driven transcription. This is the first DNA binding study of full-length p53 and its deletion variants to both intermolecular and intramolecular T.A.T triplexes. We demonstrate that the interaction of p53 with intermolecular T.A.T triplex is comparable to the recognition of CTG-hairpin non-B DNA structure. Using deletion mutants we determined the C-terminal DNA binding domain of p53 to be crucial for triplex recognition. Furthermore, strong p53 recognition of intramolecular T.A.T triplexes (H-DNA), stabilized by negative superhelicity in plasmid DNA, was detected by competition and immunoprecipitation experiments, and visualized by AFM. Moreover, chromatin immunoprecipitation revealed p53 binding T.A.T forming sequence in vivo. Enhanced reporter transactivation by p53 on insertion of triplex forming sequence into plasmid with p53 consensus sequence was observed by luciferase reporter assays. In-silico scan of human regulatory regions for the simultaneous presence of both consensus sequence and T.A.T motifs identified a set of candidate p53 target genes and p53-dependent activation of several of them (ABCG5, ENOX1, INSR, MCC, NFAT5) was confirmed by RT-qPCR. Our results show that T.A.T triplex comprises a new class of p53 binding sites targeted by p53 in a DNA structure-dependent mode in vitro and in cells. The contribution of p53 DNA structure-dependent binding to the regulation of transcription is discussed.

• MeSH
• aktivace transkripce genetika   MeSH
• DNA vazebné proteiny chemie   genetika   MeSH
• DNA chemie   genetika   MeSH
• konformace nukleové kyseliny MeSH
• lidé MeSH
• nádorový supresorový protein p53 chemie   genetika   MeSH
• nukleotidové motivy genetika   MeSH
• plazmidy genetika   MeSH
• promotorové oblasti (genetika) MeSH
• regulační oblasti nukleových kyselin genetika   MeSH
• sekvenční delece genetika   MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA vazebné proteiny MeSH
• DNA MeSH
• nádorový supresorový protein p53 MeSH
• TP53 protein, human MeSH Prohlížeč
• triplex DNA MeSH Prohlížeč

G-quadruplexes are four-stranded nucleic acid structures that are implicated in the regulation of transcription, translation and replication. Genome regions enriched in putative G-quadruplex motifs include telomeres and gene promoters. Tumour suppressor p53 plays a critical role in regulatory pathways leading to cell cycle arrest, DNA repair and apoptosis. In addition to transcriptional regulation mediated via sequence-specific DNA binding, p53 can selectively bind various non-B DNA structures. In the present study, wild-type p53 (wtp53) binding to G-quadruplex formed by MYC promoter nuclease hypersensitive element (NHE) III1 region was investigated. Wtp53 binding to MYC G-quadruplex is comparable to interaction with specific p53 consensus sequence (p53CON). Apart from the full-length wtp53, its isolated C-terminal region (aa 320-393) as well, is capable of high-affinity MYC G-quadruplex binding, suggesting its critical role in this type of interaction. Moreover, wtp53 binds to MYC promoter region containing putative G-quadruplex motif in two wtp53-expressing cell lines. The results suggest that wtp53 binding to G-quadruplexes can take part in transcriptional regulation of its target genes.

• Klíčová slova
• DNA–protein interaction, G-quadruplex, MYC, p53 protein,
• MeSH
• cirkulární dichroismus MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• DNA genetika   MeSH
• G-kvadruplexy * MeSH
• HCT116 buňky MeSH
• lidé MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• protoonkogenní proteiny c-myc genetika   metabolismus   MeSH
• regulace genové exprese MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA vazebné proteiny MeSH
• DNA MeSH
• MYC protein, human MeSH Prohlížeč
• nádorový supresorový protein p53 MeSH
• protoonkogenní proteiny c-myc MeSH
• TP53 protein, human MeSH Prohlížeč

A study of the effects of salt conditions on the association and dissociation of wild type p53 with different ~3 kbp long plasmid DNA substrates (supercoiled, relaxed circular and linear, containing or lacking a specific p53 binding site, p53CON) using immunoprecipitation at magnetic beads is presented. Salt concentrations above 200 mM strongly affected association of the p53 protein to any plasmid DNA substrate. Strikingly different behavior was observed when dissociation of pre-formed p53-DNA complexes in increased salt concentrations was studied. While contribution from the p53CON to the stability of the p53-DNA complexes was detected between 100 and 170 mM KCl, p53 complexes with circular DNAs (but not linear) exhibited considerable resistance towards salt treatment for KCl concentrations as high as 2 M provided that the p53 basic C-terminal DNA binding site (CTDBS) was available for DNA binding. On the contrary, when the CTDBS was blocked by antibody used for immunoprecipitation, all p53-DNA complexes were completely dissociated from the p53 protein in KCl concentrations≥200 mM under the same conditions. These observations suggest: (a) different ways for association and dissociation of the p53-DNA complexes in the presence of the CTDBS; and (b) a critical role for a sliding mechanism, mediated by the C-terminal domain, in the dissociation process.

• MeSH
• chlorid draselný farmakologie   MeSH
• konformace nukleové kyseliny MeSH
• nádorový supresorový protein p53 metabolismus   MeSH
• plazmidy chemie   metabolismus   MeSH
• soli farmakologie   MeSH
• vazba proteinů účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorid draselný MeSH
• nádorový supresorový protein p53 MeSH
• soli MeSH

New redox labelling of DNA by an azido group which can be chemically transformed to nitrophenyltriazole or silenced to phenyltriazole was developed and applied to the electrochemical detection of DNA-protein interactions. 5-(4-Azidophenyl)-2'-deoxycytidine and 7-(4-azidophenyl)-7-deaza-2'-deoxyadenosine nucleosides were prepared by aqueous-phase Suzuki cross-coupling and converted to nucleoside triphosphates (dNTPs) which served as substrates for incorporation into DNA by DNA polymerase. The azidophenyl-modified nucleotides and azidophenyl-modified DNA gave a strong signal in voltammetric studies, at -0.9 V, due to reduction of the azido function. The Cu-catalyzed click reaction of azidophenyl-modified nucleosides or azidophenyl-modified DNA with 4-nitrophenylacetylene gave nitrophenyl-substituted triazoles, exerting a reduction peak at -0.4 V under voltammetry, whereas the click reaction with phenylacetylene gave electrochemically silent phenyltriazoles. The transformation of the azidophenyl label to nitrophenyltriazole was used for electrochemical detection of DNA-protein interactions (p53 protein) since only those azidophenyl groups in the parts of the DNA not shielded by the bound p53 protein were transformed to nitrophenyltriazoles, whereas those covered by the protein were not.

• Publikační typ
• časopisecké články MeSH