Structural and functional innovations in the real-time evolution of new (βα) ₈ barrel enzymes

Abstract

Significance New proteins can evolve by duplication of the genes that encode them, followed by specialization of the different copies. However, how the growth rate of an organism is coupled to the changes in a protein’s structure and function occurring during this process is not known. Here we show at atomic resolution how selection for the growth of a bacterium led to the evolution of HisA proteins with either a new function or two functions (old and new). We found that a distinct protein conformation is responsible for each function, and that a better enzyme leads to faster growth only up to a certain threshold. This study provides insight into how evolution works, from atomic to whole-organism levels.