Signatures of optimal codon usage in metabolic genes inform budding yeast ecology
Fig 5
A model for ecological codon adaptation in the GALactose metabolism pathway.
The ancestral species in environment A maintains the GALactose metabolism pathway at an intermediate codon optimization. Upon introduction to environment B, which contains abundant galactose, there is increased demand for the GALactose metabolism enzymes to take advantage of this energy source. In this new environment, substitutions that increase codon optimization of the GAL genes will be selectively advantageous. Codon optimization will continue to increase under translational selection until it is no longer a barrier to expression or optimal flux through the pathway has been achieved.