Lieph, R., Veloso, F. and D.
S. Holmes. Thermophiles like Hot T.
Trends in Microbiology (in Press, 2006).
SUMMARY
A plethora of mechanisms confer protein stability in
thermophilic microorganisms and, recently, it was suggested that these
mechanisms might be divided along evolutionary lines. Here, a multi-genome
comparison shows that there is a statistically significant increase
in the proportion of NTN codons correlated with increasing optimal growth
temperature for both Bacteria and Archaea. NTN encodes exclusively non-polar,
hydrophobic amino acids and indicates a common underlying use of hydrophobicity
for stabilizing proteins in Bacteria and Archaea that transcends evolutionary
origins. However, some microorganisms do not follow this trend, suggesting
that alternate mechanisms (e.g. intracellular electrolytes) might be
used for protein stabilization. These studies highlight the usefulness
of large-scale comparative genomics to uncover novel relationships that
are not immediately obvious from protein structure studies alone.
