The nuclease hypersensitivity element III(1) upstream of the P1 promoter of c-MYC controls 85-90% of the transcriptional activation of this gene. We have demonstrated that the purine-rich strand of the DNA in this region can form two different intramolecular G-quadruplex structures, only one of which seems to be biologically relevant. This biologically relevant structure is the kinetically favo...

We have previously reported that stabilization of the G-quadruplex structures in the HIV-1 long terminal repeat (LTR) promoter suppresses viral transcription. Here we sought to develop new G-quadruplex ligands to be exploited as antiviral compounds by enhancing binding toward the viral G-quadruplex structures. We synthesized naphthalene diimide derivatives with a lateral expansion of the aromat...

To date, various G-quadruplex structures have been reported in human telomeric sequences. Human telomeric repeats can form many topological structures depending on conditions and on base modification; parallel, antiparallel, and hybrid forms. The effect of salts and some specific ligands on conformational switches between different conformers is known, but the influence of protruding sequences ...

Human telomeric DNA consists of tandem repeats of the sequence d(TTAGGG). The formation and stabilization of DNA G-quadruplexes in the human telomeric sequence have been shown to inhibit the activity of telomerase, thus the telomeric DNA G-quadruplex has been considered as an attractive target for cancer therapeutic intervention. However, knowledge of the intact human telomeric G-quadruplex str...

In-cell DEER (in-cell double electron electron resonance) is applied to investigate quadruplex formation of the human telomeric repeat d[AGGG(TTAGGG)(3)]. The initially unfolded DNA sequence forms a mixture of different quadruplex topologies upon injection into living cells. In addition, time-dependent distance measurements are carried out to monitor quadruplex folding.

In this study, we present a fluorescent switch-on probe based on a cyanovinyl-pyridinium triphenylamine (CPT) derivative that exhibited a 190-fold increase in fluorescence upon binding to G-quadruplex-forming oligonucleotide 22AG. This probe showed specificity and selectivity towards an antiparallel G-quadruplex, indicating its promising potential in G-quadruplex imaging.

Using a G-quadruplex bait, we identified the transcription co-activator Sub1 as a G-quadruplex binding protein by quantitative LC-MS/MS and demonstrated in vivo G-quadruplex binding by ChIP. In vitro, Sub1, and its human homolog PC4, bind preferentially to G-quadruplexes. This provides a possible mechanism by which G-quadruplexes can influence gene transcription.

DOTASQ (for DOTA-templated Synthetic G-quartet) is the first prototype of nature-inspired G-quadruplex ligand: its design, founded on a possible intramolecular G-quartet formation, enables it to interact with G-quadruplex DNA via an unprecedented nature-mimicking binding mode, based on the association between two G-quartets, one being native (quadruplex) and the other one artificial (ligand).

The tetramolecular PNA quadruplex motif has been probed using a dynamic covalent chemistry (DCC) approach to create and characterize a bimolecular PNA quadruplex.

It is demonstrated that even unsubstituted cationic ligands, namely the known diazoniadibenzochrysenes (, ) and the so far unreported tetraazoniapentaphenopentaphene (), stabilize quadruplex DNA upon association; the ligand exhibits essentially the same affinity towards the quadruplex as does 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H-porphine, however, with a significantly higher selectiv...