Thermodynamics of unstable DNA structures from the kinetics of the microgene PCR

Area of Science:

• Molecular Biology
• Biochemistry
• Synthetic Biology

Background:

• The microgene polymerization reaction (MPR) is a method for generating head-to-tail tandem repeats from homoduplexes (HDs).
• MPR initiation involves the alignment of HDs to form a nucleation complex, enabling DNA polymerase to create an initial doublet (ID).
• Understanding the fundamental mechanisms of MPR initiation and propagation is crucial for its application in synthetic biology.

Purpose of the Study:

• To refine the understanding of MPR initiation by incorporating thermodynamic considerations.
• To elucidate the fundamental mechanism underlying MPR propagation.
• To investigate the kinetics of MPR using different HD types and real-time PCR.

Main Methods:

• Design and synthesis of four distinct homoduplex (HD) types with varied melting temperatures and secondary structure stabilities.
• Real-time PCR was employed to monitor propagation kinetics at different temperatures.
• Thermodynamic analysis and UNAFold simulations were used to model conformational changes.

Main Results:

• A novel stage in MPR, the amplification of an initial doublet (ID) by an original HD, was identified.
• The biphasic kinetics of MPR were deciphered, revealing a two-stage process.
• The interplay between HD conformation, temperature, and DNA polymerase activity was elucidated, showing good correlation with UNAFold simulations.

Conclusions:

• MPR initiation and propagation are influenced by the thermodynamic stability of HD conformations.
• The identified amplification stage merges with propagation under specific conditions related to ID conformation stability.
• This research provides a deeper mechanistic understanding of MPR, paving the way for optimized DNA synthesis applications.