A positive correlation between GC content and growth temperature in prokaryotes

Area of Science:

• Microbiology
• Genomics
• Evolutionary Biology

Background:

• GC-rich genomes are theorized to be more heat-adapted than AT-rich genomes.
• Previous studies showed mixed results on the correlation between growth temperature and whole-genome GC content.

Purpose of the Study:

• To investigate the relationship between optimal growth temperature (Topt) and GC content in prokaryotic genomes.
• To resolve the debate on GC content and growth temperature correlations.

Main Methods:

• Phylogenetic comparative analyses of a large dataset of bacterial and archaeal genomes.
• Statistical analysis of GC content across different temperature categories (psychrophiles, mesophiles, thermophiles, hyperthermophiles).

Main Results:

• Positive correlations were observed between Topt and GC content in bacterial structural RNA genes, whole genomes, and various gene categories.
• A significant positive correlation was not found in archaea, potentially due to smaller sample sizes in previous studies.
• Including incompletely assembled archaeal genomes and excluding halophilic archaea strengthened the positive correlation between Topt and whole-genome GC content in archaea.

Conclusions:

• Prokaryotes adapted to high temperatures generally possess higher GC content.
• Thermal adaptation is a key factor, with potential contributions from enhanced DNA repair mechanisms in response to heat-induced mutagenesis.