Selection enhances protein evolvability by increasing mutational robustness and foldability

Abstract

Selection enhances mutation toleration Mutations generate variability that is either neutral or subject to natural selection. Robustness is a measure of the ability to withstand deleterious mutational effects. Zheng et al. exposed Escherichia coli populations expressing a yellow fluorescent protein to strong, weak, or no selection for yellow fluorescence for four generations. They then selected these populations to a related function, green fluorescence, for four more generations. The strong selection first for yellow and then green fluorescence resulted in the most green fluorescence and the accumulation of the most mutations. This outcome likely was due to the increased foldability of the protein. Selection thus provides a threshold for mutation accumulation, but robustness maintains a buffer necessary for protein evolution. Science , this issue p. eabb5962