Spatial Control over Reactions via Localized Transcription within Membraneless DNA Nanostar Droplets.

Area of Science:

• Synthetic biology
• Biochemistry
• Chemical engineering

Background:

• Biomolecular condensates spatially organize cellular reactions without membranes.
• Controlling reaction localization is key to understanding cellular behavior and designing synthetic systems.
• Existing methods lack precise control over reaction localization and network orchestration.

Purpose of the Study:

• To develop a programmable synthetic system for spatiotemporally controlling chemical reactions using membraneless droplets.
• To investigate the impact of localized transcription and product diffusion on reaction kinetics.
• To demonstrate independent control of multiple reaction networks within distinct droplets.

Main Methods:

• Utilized DNA nanostar (NS) droplets for in vitro liquid-liquid phase separation, creating programmable membraneless compartments.
• Localized transcription templates within different NS droplet types to spatially segregate reaction components.
• Analyzed RNA concentration gradients and their effect on toehold-mediated strand displacement reaction rates.

Main Results:

• Demonstrated successful partitioning of substrates and localization of transcription within NS droplets.
• Observed formation of RNA concentration gradients due to droplet-localized transcription and bulk degradation.
• Showcased 2-fold slower reaction rates distant from transcription sites, confirming gradient effects.
• Achieved independent formation and maintenance of multiple gradients using distinct NS droplet types.

Conclusions:

• Developed a novel synthetic system for spatially localized reaction control without physical membranes.
• Established a platform for studying reaction kinetics and product exchange in protocell-like environments.
• Provides a foundation for engineering complex, spatially organized chemical reaction networks in synthetic systems.