Enzyme recruitment and the evolution of new metabolic potential

Abstract

Processes such as the acquisition of antibiotic resistance by pathogenic bacteria and the bioremediation of anthropogenic toxins by microorganisms demonstrate that the evolution of new biological catalysts is an ongoing process. What is the origin of these new activities, and how do they evolve to yield highly specialized enzymes? The answers to these questions are not well understood, especially at the molecular level. The goal of our research is to combine microbial genetic selection strategies with mechanistic enzymology to identify new catalysts and investigate their evolutionary potential. In this presentation, I will discuss recent experiments in our laboratory in which we challenged E. coli K‐12 for growth on several metabolically inert compounds. High‐level expression of specific genes was found to afford an expansion of the metabolic capabilities of this bacterium by virtue of latent catalytic activities embedded within the genome. I will discuss the experimental strategies that led to the identification of these promiscuous catalysts and describe the preliminary characterization of these activities. The implications of these findings upon the natural and directed evolution of enzymes with useful applications will also be discussed.