Biomolecular stability and life at high temperatures

Area of Science:

• Biochemistry
• Astrobiology
• Molecular Biology

Background:

• The upper temperature limit for life remains undefined.
• Molecular instability is hypothesized to be the primary limiting factor.
• Hyperthermophiles thrive at extreme temperatures, necessitating robust biomolecular structures.

Purpose of the Study:

• To review the thermal stability of intracellular small molecules/metabolites and macromolecules.
• To investigate mechanisms that enable life at high temperatures.
• To assess the potential upper temperature limits for life based on molecular stability.

Main Methods:

• Literature review of in vitro and in vivo studies on biomolecule thermal stability.
• Examination of small molecules, proteins, DNA, RNA, and lipids.
• Analysis of cellular strategies for managing molecular instability at high temperatures.

Main Results:

• Some small molecules exhibit in vitro instability but are managed in vivo by cellular mechanisms.
• Proteins show potential stability beyond current life-supporting temperatures, with limited data above 100°C.
• DNA stability is maintained by salt, polyamines, proteins, and supercoiling; RNA stability involves covalent modification and structure; lipids are highly stable.

Conclusions:

• Cellular mechanisms effectively manage the in vitro instability of certain small molecules.
• Major macromolecules like proteins, DNA, RNA, and lipids possess inherent stability or adaptive strategies for high-temperature environments.
• While in vitro data suggest higher temperature limits, in vivo implications and data remain challenging to assess.