Sequence-encoded interactions program internal condensate architecture.

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Cellular condensates like nucleoli and stress granules possess internal multiphase organization crucial for function.
• The mechanisms governing the establishment of this internal organization are not fully understood.

Purpose of the Study:

• To elucidate how molecular interactions encode precise multiphase architecture within cellular condensates.
• To establish a general framework for programming hierarchical self-assembly and organizing biological matter.

Main Methods:

• Utilized a programmable DNA system to investigate the role of molecular interactions in condensate organization.
• Developed an associative polymer model to capture the observed relationships between interaction energy and molecular partitioning.
• Engineered condensates with up to four coexisting phases.

Main Results:

• Phase separation amplifies subtle differences in homotypic interaction energies into dominant organizational forces.
• A critical interaction energy threshold is required to initiate internal demixing.
• Molecular partitioning scales nearly linearly with interaction strength, a relationship captured by the associative polymer model.
• Demonstrated the ability to engineer condensates with significant viscosity differences (100-fold) within a single droplet.

Conclusions:

• Molecular interactions precisely encode multiphase architecture in cellular condensates.
• The discovered design principles are general and applicable to biological systems like RNA-peptide interactions.
• Provides a framework for programming hierarchical self-assembly and controlling biological matter organization.