Recent experiments provide fascinating examples of how G4 DNA and G4 RNA structures--aka quadruplexes--may contribute to normal biology and to genomic pathologies. Quadruplexes are transient and therefore difficult to identify directly in living cells, which initially caused skepticism regarding not only their biological relevance but even their existence. There is now compelling evidence for f...

Thioflavin T (ThT) becomes fluorescent in the presence of the G-quadruplex structure such as that formed by the human telomeric motif. In this report, we extend and generalize these observations and show that this dye may be used as a convenient and specific quadruplex probe. In the presence of most, but not all, G4-forming sequences, we observed a large increase in ThT fluorescence emission, w...

Guanine-rich sequences can fold into four-stranded structures of stacked guanine-tetrads, so-called G-quadruplexes (G4). These unique motifs have been extensively studied on the DNA level; however, exploration of the biological roles of G4s at the RNA level is just emerging. Here we show that G4 RNA when introduced within coding regions are capable of stimulating -1 ribosomal frameshifting (-1 ...

The electrical conduction properties of G4-DNA are investigated using a hybrid approach, which combines electronic structure calculations, molecular dynamics (MD) simulations and the formulation of an effective tight-binding model Hamiltonian. Charge transport is studied by computing transmission functions along the MD trajectories. Though G4-DNA is structurally more stable than dsDNA, our resu...

Genotype 4 chronic hepatitis C (G4 HCV) accounts for 13% of worldwide HCV infections; with 10 million people infected with the virus across the world. Up to the end of 2013, the only treatment option for G4 HCV was treatment with pegylated interferon and ribavirin for 24-48 weeks. Since late 2013, treatment of G4 HCV has been transformed by the licensing of many directly acting antiviral agents...

Synthetic polymers of a specific shape and size play major role in drug delivery systems. Dendrimers are unique synthetic macromolecules of nanometer dimensions with a highly branched structure and globular shape with potential applications in gene and drug delivery. We examine the interaction of several dendrimers of different compositions mPEG-PAMAM (G3), mPEG-PAMAM (G4) and PAMAM (G4) with h...

Burkholderia vietnamiensis has both the cepIR quorum-sensing system that is widely distributed among the Burkholderia cepacia complex (BCC) and the bviIR system. Comparison of the expression of cepI, cepR, bviI, and bviR-luxCDABE fusions in B. vietnamiensis G4 and the G4 cepR and bviR mutants determined that the expression of bviI requires both a functional cognate regulator, BviR, and function...

DNA and RNA guanine-quadruplexes (G4s) are stabilized by several cations, in particular by potassium and sodium ions. Generally, potassium stabilizes guanine-quartet assemblies to a larger extent than sodium; in this article we report about a higher-order G4 structure more stable in sodium than in potassium. Repeats of the DNA GGGTTA telomeric motif fold into contiguous G4 units. Using three in...

Structure-specific ligands are convenient tools for the recognition, targeting or probing of non-canonical DNA structures. Porphyrin derivatives exhibit a preference for interaction with G-quadruplex (G4) structures over canonical duplex DNA and are able to cause photoinducible damage to nucleic acids. Here, we show that Zn(II) 5,10,15,20-tetrakis(N-carboxymethyl-4-pyridinium)porphyrin ( ZNP1: ...

Guanine rich nucleic acid sequences can form G-quadruplex (G4) structures that interfere with DNA replication, repair and RNA transcription. The human FANCJ helicase contributes to maintaining genomic integrity by promoting DNA replication through G4-forming DNA regions. Here, we combined single-molecule and ensemble biochemical analysis to show that FANCJ possesses a G4-specific recognition si...