Design and Characterization of a Gene-Encoding DNA Nanoparticle in a Cell-Free Transcription-Translation System

Area of Science:

• Biotechnology
• Molecular Biology
• Nanotechnology

Background:

• DNA nanotechnology enables gene-encoded DNA origami nanoparticles (NPs) for potential gene therapy.
• Studying DNA NP effects on gene expression in cells is challenging due to delivery and intracellular factors.
• A cell-free system provides a controlled environment to isolate and study DNA NP gene expression.

Purpose of the Study:

• To develop and validate a cell-free method for assessing gene expression from DNA origami nanoparticles.
• To investigate the impact of DNA NP structural design and promoter sequence on gene expression.
• To demonstrate the utility of cell-free transcription-translation (TXTL) systems in DNA NP research.

Main Methods:

• Utilized a pure *E. coli*-derived cell-free transcription-translation (TXTL) system.
• Engineered a 12-helix bundle DNA origami nanoparticle displaying an optimized *Renilla luciferase* gene.
• Employed luciferase-based bioluminescence assays to quantify protein expression levels.

Main Results:

• Gene transcription from folded DNA NPs was observed, though at a reduced rate compared to double-stranded DNA.
• DNA NPs with promoters designed for single-stranded DNA (ssDNA) form showed decreased protein expression.
• Replacing the promoter with an arbitrary sequence substantially reduced protein expression.

Conclusions:

• Cell-free TXTL systems are effective for studying gene expression from DNA origami nanoparticles.
• DNA NP structural design and promoter configuration critically influence gene expression outcomes.
• This approach facilitates the optimization of DNA NPs for gene therapy and other applications.