超好熱菌の高温適応戦略

抄録

Hyperthermophiles are organisms that display optimal growth temperatures of 80˚C or higher. They thrive in a variety of hydrothermal environments. Hyperthermophiles occupy the most early-branching lineages in the phylogenetic tree of life, and are a focus of attention in terms of the origin and evolution of life. Hyperthermophiles display diversity in their mechanisms to conserve energy. The biomolecules of hyperthermophiles must function at extremely high temperatures, and this is made possible by unique structural features and/or interactions. Nucleic acids are stabilized by enzymes such as reverse gyrase and interactions with thermostable DNA-binding proteins or compounds including branched-chain polyamines. Proteins display structural adaptations that enable them to maintain their functional conformation at high temperatures. Hyperthermophiles from the archaea display much higher growth temperatures compared to their bacterial counterparts, and utilize membrane lipids not found in bacteria or eukaryotes. Metabolic enzymes and pathways are also designed to avoid unnecessary thermal degradation of labile intermediates. This article will provide an overview of the fascinating world of hyperthermophiles and the strategies that allow them to thrive at temperatures that would be lethal to any other organism.