Title:
Life in Extreme Environments: How Do the Proteins Work?

Abstract:
Life has been found in many extremes of pressure P, temperature T, and chemical composition X. There are speculations that life on Earth may have originated in deep-sea hydrothermal vents at high P and T and that life on Mars may exist deep subsurface, also at high P and T. This leads to the question of how proteins necessary for life can function at extreme P-T-X. Our focus is mainly on extremes of pressure. First, we will discuss how P and T affect the enzyme dihydrofolate reductase (DHFR), and how DHFR from piezophilic (pressure-loving) microbes are adapted relative to homologous DHFR from mesophilic (moderate-loving) microbes. Next, we will discuss how early proteins may have utilized salts in the environment to extend functional control beyond their amino acid sequence, and how P could affect this.