Emergence of population-level feedback control by transposon-plasmid coevolution

Area of Science:

• Evolutionary biology
• Microbial genetics
• Systems biology

Background:

• Adaptive functions' origins are poorly understood.
• Escherichia coli strains with high-copy plasmids are used to study evolution.
• Green fluorescent protein (GFP) expression in response to tetracycline is investigated.

Purpose of the Study:

• To investigate the de novo evolution of population-level feedback control in Escherichia coli.
• To understand how selection maintains plasmids within single cells.
• To analyze the relationship between GFP expression, bacterial fitness, and tetracycline response.

Main Methods:

• Utilized clonal Escherichia coli strains with high-copy plasmids.
• Introduced a tetA-gfp tetracycline resistance transposon.
• Applied selection pressures related to tetracycline and plasmid dynamics.

Main Results:

• Observed the de novo evolution of population-level feedback control.
• Demonstrated that selection maintains tetA+ and tetA- plasmids via negative feedback.
• Showed that small mutations can lead to significant changes in population behavior.

Conclusions:

• The evolution of polymorphic intracellular plasmid populations enables dynamic host responses to antibiotics.
• Feedback control mechanisms can rapidly evolve in microbial populations.
• This provides a model for understanding the evolution of adaptive functions.