A modular DNA toolkit for single-molecule biophysics

A toolkit designed for crafting custom DNA molecules has emerged, revolutionizing single-molecule biophysics. The novel modular DNA (ModDNA) toolkit surpasses traditional approaches, such as the lambda-phage genome, which have constrained variables like sequence uniformity and limited modifiability. By merging computational sequence design with cloning, the ModDNA toolkit now generates long DNA constructs, reaching up to 100 kilobases, with completely user-defined sequences.

The toolkit employs an in silico sequence design with curated databases to generate a motif-depleted sequence backbone. Users can then insert their desired sequence into any position within this backbone. Subsequently, Golden Gate assembly assembles these sequences into functional constructs. The researchers demonstrate the ability to precisely position local features, such as a fluorophore, a bound protein, and a DNA-origami structure, within these constructs.

The applications of the ModDNA toolkit are vast, particularly in single-molecule visualization assays. One such example is the visualization of DNA loop extrusion by human condensin I. The toolkit provides a scalable, sequence-programmable alternative to the lambda-DNA and other restrictive substrates, broadening the scope of biophysical research.

Moreover, the motif-aware feature-free design encourages connections between single-molecule biophysics and other emerging fields, like machine-guided regulatory-sequence design and synthetic-genome engineering. These interdisciplinary links are becoming increasingly vital as researchers strive to control programmable sequence context.