The Structural Biology of Catalase Evolution

Abstract

Catalases are crucial enzymes enabling aerobic and anaerobic metabolism in an oxygenated atmosphere, by readily eliminating hydrogen peroxide. Monofunctional heme catalases, catalase-peroxidases and Mn catalases constitute a classic example of convergent evolution since they evolved independently more than two billion years ago, and are widespread over all life forms. Heme catalase clades I and III seem to have evolved from a clade II ancestor that lost an aßa extra domain, while many other heme catalases remain to be classified. Catalase-peroxidases have been surprisingly conserved throughout evolution, and also harness the oxidative power of hydrogen peroxide to oxidize varied substrates. Mn catalases are particularly abundant among enterobacterial pathogens and strict anaerobes, indicative of their key role at withstanding microaerophilic conditions and oxidative stress of the host defense response. Such functional and structural diversity make these enzymes particularly suitable, not only for metabolic engineering applications, development of biosensors, and as targets for antimicrobial drug design; but also enlighten our understanding of protein evolution.