Limits...
The guanine-quadruplex structure in the human c-myc gene's promoter is converted into B-DNA form by the human poly(ADP-ribose)polymerase-1.

Fekete A, Kenesi E, Hunyadi-Gulyas E, Durgo H, Berko B, Dunai ZA, Bauer PI - PLoS ONE (2012)

Bottom Line: We surmise that h PARP-1 binds to the GQ structure and participates in the conversion of that structure into the transcriptionally more active B-DNA form.The first Zn-finger structure present in h PARP-1 participates in this interaction.PARP-1 might be a new member of the group of proteins participating in the regulation of transcription through their interactions with GQ structures present in the promoters of different genes.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary.

ABSTRACT
The important regulatory role of the guanine-quadruplex (GQ) structure, present in the nuclease hypersensitive element (NHE) III(1) region of the human c-myc (h c-myc) gene's promoter, in the regulation of the transcription of that gene has been documented. Here we present evidences, that the human nuclear poly(ADP-ribose)polymerase-1 (h PARP-1) protein participates in the regulation of the h c-myc gene expression through its interaction with this GQ structure, characterized by binding assays, fluorescence energy transfer (FRET) experiments and by affinity pull-down experiments in vitro, and by chromatin immunoprecipitation (ChIP)-qPCR analysis and h c-myc-promoter-luciferase reporter determinations in vivo. We surmise that h PARP-1 binds to the GQ structure and participates in the conversion of that structure into the transcriptionally more active B-DNA form. The first Zn-finger structure present in h PARP-1 participates in this interaction. PARP-1 might be a new member of the group of proteins participating in the regulation of transcription through their interactions with GQ structures present in the promoters of different genes.

Show MeSH

Related in: MedlinePlus

PARP-1 modifies the effect of increasing temperature on the FRET activities of the F-c-myc GQ-R molecule.FRET melting curves were taken in the absence or in the presence of 1 µg h PARP-1 and using a 2°C/2 min temperature gradient. Excitation was at 485 nm and emission was recorded at 585 nm. From the recorded data ΔFRET/ΔT values were calculated and plotted (ordinate) versus the applied temperatures (abscissa).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3412819&req=5

pone-0042690-g004: PARP-1 modifies the effect of increasing temperature on the FRET activities of the F-c-myc GQ-R molecule.FRET melting curves were taken in the absence or in the presence of 1 µg h PARP-1 and using a 2°C/2 min temperature gradient. Excitation was at 485 nm and emission was recorded at 585 nm. From the recorded data ΔFRET/ΔT values were calculated and plotted (ordinate) versus the applied temperatures (abscissa).

Mentions: The c-myc GQ structure is one of the several isomorphic structures which are not characterized in details [38]–[41]. When those are transformed into each other, their oligonucleotide chains make movements, during which their two ends might get closer or move further from each other. The FRET method can follow these movements being the FRET intensity a function of the distance of the two fluorophores. Therefore we followed the FRET intensity changes during the melting of the single-stranded h c-myc GQ DNA structure in the absence and in the presence of h PARP-1. The temperature of the sample holding cuvette was increased with a constant rate (2°C/2 min) and the FRET values were recorded. From the data a secondary differential plot has been created and the ΔFRET/ΔT values were spotted versus the temperature. At Fig. 4 large oscillatory changes in the ΔFRET/ΔT values were seen in the first part of the curve between 25 and 35°C and which presumably were the consequence of conversions of certain isomorphic structures into another, different isomorphic form. The second part of the curve was nearly parallel with the abscissa, meaning a continuous decrease of the FRET as temperature was gradually increasing. In the presence of h PARP-1 the amplitude values of changes were decreased and the curve was smoothed out. PARP-1 might have served as a sink and stabilized one of the isomorphs. In the presence of the complementary chain this isomorphic structure might be converted directly either into the B-DNA form or with the help of other transcriptional factors into the preinitiation complex.


The guanine-quadruplex structure in the human c-myc gene's promoter is converted into B-DNA form by the human poly(ADP-ribose)polymerase-1.

Fekete A, Kenesi E, Hunyadi-Gulyas E, Durgo H, Berko B, Dunai ZA, Bauer PI - PLoS ONE (2012)

PARP-1 modifies the effect of increasing temperature on the FRET activities of the F-c-myc GQ-R molecule.FRET melting curves were taken in the absence or in the presence of 1 µg h PARP-1 and using a 2°C/2 min temperature gradient. Excitation was at 485 nm and emission was recorded at 585 nm. From the recorded data ΔFRET/ΔT values were calculated and plotted (ordinate) versus the applied temperatures (abscissa).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3412819&req=5

pone-0042690-g004: PARP-1 modifies the effect of increasing temperature on the FRET activities of the F-c-myc GQ-R molecule.FRET melting curves were taken in the absence or in the presence of 1 µg h PARP-1 and using a 2°C/2 min temperature gradient. Excitation was at 485 nm and emission was recorded at 585 nm. From the recorded data ΔFRET/ΔT values were calculated and plotted (ordinate) versus the applied temperatures (abscissa).
Mentions: The c-myc GQ structure is one of the several isomorphic structures which are not characterized in details [38]–[41]. When those are transformed into each other, their oligonucleotide chains make movements, during which their two ends might get closer or move further from each other. The FRET method can follow these movements being the FRET intensity a function of the distance of the two fluorophores. Therefore we followed the FRET intensity changes during the melting of the single-stranded h c-myc GQ DNA structure in the absence and in the presence of h PARP-1. The temperature of the sample holding cuvette was increased with a constant rate (2°C/2 min) and the FRET values were recorded. From the data a secondary differential plot has been created and the ΔFRET/ΔT values were spotted versus the temperature. At Fig. 4 large oscillatory changes in the ΔFRET/ΔT values were seen in the first part of the curve between 25 and 35°C and which presumably were the consequence of conversions of certain isomorphic structures into another, different isomorphic form. The second part of the curve was nearly parallel with the abscissa, meaning a continuous decrease of the FRET as temperature was gradually increasing. In the presence of h PARP-1 the amplitude values of changes were decreased and the curve was smoothed out. PARP-1 might have served as a sink and stabilized one of the isomorphs. In the presence of the complementary chain this isomorphic structure might be converted directly either into the B-DNA form or with the help of other transcriptional factors into the preinitiation complex.

Bottom Line: We surmise that h PARP-1 binds to the GQ structure and participates in the conversion of that structure into the transcriptionally more active B-DNA form.The first Zn-finger structure present in h PARP-1 participates in this interaction.PARP-1 might be a new member of the group of proteins participating in the regulation of transcription through their interactions with GQ structures present in the promoters of different genes.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary.

ABSTRACT
The important regulatory role of the guanine-quadruplex (GQ) structure, present in the nuclease hypersensitive element (NHE) III(1) region of the human c-myc (h c-myc) gene's promoter, in the regulation of the transcription of that gene has been documented. Here we present evidences, that the human nuclear poly(ADP-ribose)polymerase-1 (h PARP-1) protein participates in the regulation of the h c-myc gene expression through its interaction with this GQ structure, characterized by binding assays, fluorescence energy transfer (FRET) experiments and by affinity pull-down experiments in vitro, and by chromatin immunoprecipitation (ChIP)-qPCR analysis and h c-myc-promoter-luciferase reporter determinations in vivo. We surmise that h PARP-1 binds to the GQ structure and participates in the conversion of that structure into the transcriptionally more active B-DNA form. The first Zn-finger structure present in h PARP-1 participates in this interaction. PARP-1 might be a new member of the group of proteins participating in the regulation of transcription through their interactions with GQ structures present in the promoters of different genes.

Show MeSH
Related in: MedlinePlus