A new DNA sensor system for specific and quantitative detection of mycobacteria.

In the current study, we describe a novel DNA sensor system for specific and quantitative detection of mycobacteria, which is the causative agent of tuberculosis. Detection is achieved by using the enzymatic activity of the mycobacterial encoded enzyme topoisomerase IA (TOP1A) as a biomarker. The presented work is the first to describe how the catalytic activities of a member of the type IA family of topoisomerases can be exploited for specific detection of bacteria.

Interlinked DNA nano-circles for measuring topoisomerase II activity at the level of single decatenation events.

DNA nano-structures present appealing new means for monitoring different molecules. Here, we demonstrate the assembly and utilization of a surface-attached double-stranded DNA catenane composed of two intact interlinked DNA nano-circles for specific and sensitive measurements of the life essential topoisomerase II (Topo II) enzyme activity. Topo II activity was detected via the numeric release of DNA nano-circles, which were visualized at the single-molecule level in a fluorescence microscope upon isothermal amplification and fluorescence labeling.

Optimized Detection of Plasmodium falciparum Topoisomerase I Enzyme Activity in a Complex Biological Sample by the Use of Molecular Beacons.

The so-called Rolling Circle Amplification allows for amplification of circular DNA structures in a manner that can be detected in real-time using nucleotide-based molecular beacons that unfold upon recognition of the DNA product, which is being produced during the amplification process. The unfolding of the molecular beacons results in a fluorescence increase as the Rolling Circle Amplification proceeds. This can be measured in a fluorometer.