Accelerating pathway evolution by increasing the gene dosage of chromosomal segments

Area of Science:

• Microbiology
• Synthetic Biology
• Metabolic Engineering

Background:

• Experimental evolution accelerates adaptation but often relies on chance events like increased gene dosage.
• Targeted gene amplification offers a way to induce beneficial mutations and speed up evolution.

Purpose of the Study:

• To develop a method for inducing targeted chromosomal segment amplification to facilitate rapid evolution.
• To apply this method to engineer microbes for the catabolism of lignin-derived aromatic compounds.

Main Methods:

• Developed the Evolution by Amplification and Synthetic Biology (EASy) method to create tandem arrays of chromosomal regions.
• Applied EASy to *Acinetobacter baylyi* for the degradation of guaiacol, a lignin product.
• Identified and characterized *Amycolatopsis* genes (*gcoAB*) involved in guaiacol catabolism.

Main Results:

• EASy successfully generated strains capable of utilizing guaiacol as a sole carbon source within approximately 1,000 generations.
• Discovered *gcoAB* genes encoding a cytochrome P450 enzyme that converts guaiacol to catechol.
• Observed the emergence of evolved alleles, including fusions between GcoA and CatA, conferring enhanced guaiacol metabolism.

Conclusions:

• Harnessing chromosomal gene amplification via EASy significantly accelerates the evolution of desirable traits in microbes.
• This approach has potential applications in metabolic engineering and synthetic biology for biofuel production and bioremediation.
• EASy provides a powerful tool for directed evolution, overcoming limitations of traditional methods.