Genomic correlates of hyperthermostability, an update.

Area of Science:

• Microbial genomics
• Extremophile biology
• Proteomics

Background:

• A previous study identified a charge-to-polar (CvP) amino acid bias as a signature of hyperthermophilic organisms (growth temperature >80°C).
• The doubling of available microbial genome sequences necessitates re-evaluation of this empirical rule.

Purpose of the Study:

• To re-analyze genomic data with an expanded dataset to confirm or refute the CvP-bias rule for hyperthermophiles.
• To identify genomic correlates of hyperthermostability using a wider range of microbial genomes.
• To compare the discriminatory power of CvP-bias with other proposed correlates of hyperthermostability.

Main Methods:

• Re-analysis of genomes from 9 thermophiles, 9 hyperthermophiles, and 53 mesothermophile microorganisms.
• Principal Component Analysis (PCA) to assess discriminating factors.
• Evaluation of proteome average isoelectric point (pI) and dinucleotide statistical index.

Main Results:

• The CvP-bias was confirmed as a valid signature for hyperthermophiles across the expanded dataset.
• CvP-bias emerged as the optimal and most discriminating factor in PCA between hyperthermophilic and mesothermophilic microorganisms.
• CvP-bias proved to be the sole criterion capable of clearly distinguishing hyperthermophiles from mesothermophiles on a global genomic scale.

Conclusions:

• The CvP-bias is a robust and optimal genomic criterion for identifying hyperthermophilic microorganisms.
• This finding reinforces the utility of amino acid composition as a predictor of extremophile adaptation.
• The CvP-bias provides a reliable global genomic basis for distinguishing hyperthermophiles from mesothermophiles.