Evolution of a minimal cell

Area of Science:

• Synthetic biology
• Evolutionary biology
• Microbiology

Background:

• Minimal cells, possessing only essential genes, offer insights into life's fundamental processes.
• Understanding evolutionary dynamics in simplified organisms is crucial for various applications.

Purpose of the Study:

• To compare the evolutionary trajectory of an engineered minimal cell with its non-minimal progenitor.
• To investigate the impact of genome minimization on mutation rates, fitness, and adaptation.

Main Methods:

• Comparative evolution experiment between a synthetic minimal cell and Mycoplasma mycoides.
• Monitoring mutation rates, fitness, growth rate, and cell size over 2,000 generations.
• Analysis of genetic targets and epistatic effects, particularly mutations in ftsZ.

Main Results:

• Minimal cells exhibited high mutation rates, comparable to other bacteria, unaffected by genome size.
• Initial fitness reduction in minimal cells was recovered within 2,000 generations.
• Minimal cells evolved 39% faster in relative fitness than non-minimal cells.
• Cell size evolution was constrained in minimal cells, unlike the significant increase in non-minimal cells, due to ftsZ mutations.

Conclusions:

• Natural selection rapidly improves the fitness of engineered minimal cells.
• Genome streamlining presents evolutionary challenges and constraints, particularly regarding cell morphology.
• Insights into minimal cell evolution inform understanding of endosymbionts, biotechnology chassis, and synthetic cell refinement.