Multiscale topological analysis of kinetoplast DNA via high-resolution AFM

Area of Science:

• Nanoscale biology
• Parasitology
• Biophysics

Background:

• Kinetoplast DNA (kDNA) is a crucial network of DNA circles in parasitic mitochondria.
• Its complex topology and mechanical properties are not fully understood.
• Previous studies suggest tuneable mechanics but lack detailed structural analysis.

Purpose of the Study:

• To perform a multiscale analysis of kDNA structure using advanced imaging techniques.
• To quantify population properties and investigate localized variations in kDNA.
• To elucidate the contested topology of kDNA and its mechanical implications.

Main Methods:

• High-resolution atomic force microscopy (AFM) was employed to capture detailed kDNA images.
• Custom-designed image analysis protocols were developed for quantitative assessment.
• Single molecule studies and selective DNA digestion were used to probe network properties.

Main Results:

• Observed geometric fluctuations in area and mean curvature, correlating with in vitro data.
• Quantified a decrease in DNA density from the kDNA periphery to the center, with increasing pore size.
• Node connectivity exceeded mean valence, exhibiting positional dependence and a bimodal distribution in separation.

Conclusions:

• High-resolution AFM combined with image analysis offers a powerful method for studying complex nanoscale structures.
• The findings provide critical data for characterizing kDNA topology, aiding understanding of its biological and mechanical functions.
• This research contributes to the ongoing effort to resolve the structural intricacies of kDNA in parasites.