Recombinase-Controlled Multiphase Condensates Accelerate Nucleic Acid Amplification and CRISPR-Based Diagnostics.

Area of Science:

• Molecular Biology
• Biophysics
• Biochemistry

Background:

• Isothermal nucleic acid amplification techniques are vital for diagnostics and genotyping.
• Recombinase polymerase amplification (RPA) offers field-deployable nucleic acid amplification at moderate temperatures.
• CRISPR-based detection enhances diagnostic accuracy when integrated with amplification methods.

Purpose of the Study:

• To investigate the regulatory mechanisms of recombinase polymerase amplification (RPA).
• To explore the role of liquid-liquid phase separation in RPA efficiency.
• To identify key protein components and their functions in RPA-mediated condensate formation.

Main Methods:

• Utilized volumetric imaging assays to visualize RPA condensates and reaction dynamics.
• Investigated the function of T4 UvsX recombinase and its C-terminus in phase separation.
• Assessed the impact of condensate structure on amplification efficiency, including reverse transcription-RPA.
• Characterized a UvsX^D274A mutant for its phase-separation properties.

Main Results:

• Discovered that RPA is controlled by liquid-liquid phase separation, with condensate formation enhancing amplification.
• Identified T4 UvsX recombinase as the key regulator of multiphase condensates, with its C-terminus crucial for phase separation.
• Demonstrated that spatial organization within condensates optimizes amplification, while disruption reduces efficiency.
• Showcased that the UvsX^D274A mutant enhances RNA detection in RPA-coupled CRISPR diagnostics.

Conclusions:

• RPA functions as a multiphase condensate, with protein organization dictating amplification efficiency.
• The UvsX^D274A mutant exhibits altered phase-separation properties and improves RNA detection in diagnostic applications.
• Understanding RPA's phase-separation behavior offers new avenues for optimizing nucleic acid amplification and diagnostics.