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How Do You Live in Hell?

How Do You Live in Hell?

Chapter:
(p.90) 3 How Do You Live in Hell?
Source:
Microbes from Hell
Author(s):
Patrick Forterre, Teresa Lavender Fagan
Publisher:
University of Chicago Press
DOI:10.7208/chicago/9780226265964.003.0004

A more technical chapter in which the author describes the molecular adaptations allowing hyperthermophiles thriving in hell. The chapter starts with reminder of the role of water and carbon in the chemistry of life and the importance of both strong (covalent) and weak chemical bonds in the architecture of macromolecules. The two types of damages affecting these bonds at high temperature, thermodegradation and thermodenaturation, respectively, are discussed, explaining the range of temperatures suitable for life on Earth. The mechanisms protecting proteins, nucleic acids and lipids against thermodegradation and thermodenaturation are described with reminders of the role of these macromolecules in cell physiology. This includes an experiment showing that circular DNA is stable up to 110°C, thanks to topological links between the two DNA strands. RNA is very fragile at high temperature and the author suggests that requirement for messenger RNA stability in eukaryotes could explain why there is no hyperthermophilic eukaryote. Membrane permeability appears to be the Achille’s heel of cells at high temperature and the unique phospholipids of archaea probably explain why most hyperthermophiles belong to this domain. Reading this chapter led you concluding that microbes from hell are not primitive organisms but marvels of adaptation

Keywords:   thermodegradation, thermodenaturation, extremenzyme, thermostable proteins, DNA stability, RNA world, DNA topoisomerase, membrane permeability, Phospholipids, ATP synthase

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