Implication of Enzymes in the Adaptation of Extremophilic Microbes

Abstract

AbstractExtremophiles belong to prokaryotes and eukaryotes, which can survive and thrive in hostile environments where conditions are supposed to be lethal. These organisms have developed different strategies to counteract the stress in their environment and to maintain their physiological properties, for instance, enzymes known as extremozymes are adapted to function even under unusual conditions. This chapter summarizes the enzyme adaptation mechanisms of extremophilic microbes, providing insights into the key role of these enzymes in the microbial adaptation to unfavorable conditions imposed by harsh environments. Extremophiles have certain modifications in their enzymes in order to retain their functions in adverse conditions, which, on the contrary, would aggregate, precipitate, or denature an enzyme from a non-extremophile. To maintain their function at high temperatures, thermophilic enzymes often have a prominent hydrophobic core and enhanced electrostatic contacts. At the same time, to conserve their flexibility and function at low temperatures, psychrophilic enzymes have a reduced hydrophobic core and less charged protein surface. Furthermore, halophilic, acidophilic, and alkaliphilic enzymes are characterized by increased negative surface charge, thus enhancing their acidic amino acid content and peptide insertions. This would compensate for the extreme ionic conditions. Enzymes from piezophilic microbes are generally characterized by low stability and high compressibility. Understanding extremophilic enzyme functioning and adaption mechanisms enables not only the understanding of the origins of life on Earth but also opens new prospects for developing and employing a new generation of enzymes required in biotechnological processes.KeywordsExtremophilesExtremozymesAdaptationStability