Tuning evolvability via plasmid copy number and regulatory architecture

Area of Science:

• Synthetic biology
• Evolutionary biology
• Microbiology

Background:

• Genetic modules are engineered using principles from physical and biochemical systems.
• The impact of evolution and mutations on genetic module performance is often overlooked in design.
• Understanding mutation dynamics is crucial for robust biocircuit development.

Purpose of the Study:

• To investigate how gene dosage (plasmid copy number) and regulatory architecture influence phenotypic mutation rates.
• To characterize the interplay between genetic design elements and evolutionary pressures.
• To provide insights for designing evolutionarily stable and evolvable biocircuits.

Main Methods:

• Computational modeling of genetic systems.
• In vivo mutagenesis experiments in Escherichia coli.
• Analysis of phenotypic mutation rates under varying gene dosage and regulatory conditions.

Main Results:

• Increased plasmid copy number (PCN) promotes gain-of-function mutations but hinders loss-of-function mutations.
• Mutations in coding regions are often phenotypically masked.
• Regulatory region mutations become more apparent with increasing PCN, regardless of regulatory strategy.

Conclusions:

• Gene dosage and regulatory architecture are key determinants of mutation impact in genetic modules.
• The location of mutations (coding vs. regulatory regions) affects their phenotypic visibility.
• Findings inform the rational design of biocircuits that balance evolutionary stability and evolvability.