Folding Kinetics of Single Human Telomeric G-Quadruplex Affected by Cisplatin.

G-Quadruplex DNA structure has been proven to be a binding target for small molecular organic compounds and hence regarded as a promising pharmacological target. Cisplatin is a widely used chemotherapy drug that targets duplex DNA and was recently shown to react also with G-quadruplex, implying that cisplatin actually may also target G-quadruplex. In this work, we employed magnetic tweezers to investigate the influence of cisplatin on the folding kinetics of single human telomeric G-quadruplex.

Pif1 is a force-regulated helicase.

Pif1 is a prototypical member of the 5' to 3' DNA helicase family conserved from bacteria to human. It has a high binding affinity for DNA, but unwinds double-stranded DNA (dsDNA) with a low processivity. Efficient DNA unwinding has been observed only at high protein concentrations that favor dimerization of Pif1.

Complex kinetics of DNA condensation revealed through DNA twist tracing.

Toroid formation is an important mechanism for DNA condensation in cells. The length change during DNA condensation was investigated in previous single-molecule experiments. However, DNA twist is key to understanding the topological kinetics of DNA condensation.