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Preferred codons and amino acid couples in hyperthermophiles
Sávio Torres De Farias1, Maria Christina Manhães Bonato
1Departamento de Biologia Molecular, Universidade Federal da Paraíba, João Pessoa-PB, 58059-900, Brazil.
Genome Biology
|August 21, 2002
Summary
Prokaryotes withstand extreme heat due to specific amino acid ratios and codon usage. Higher glutamate (E) and lysine (K) percentages, with lower glutamine (Q) and histidine (H), indicate thermal adaptation in heat-loving organisms.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Most organisms thrive between 20-50°C.
- Some prokaryotes, including Archaea and Bacteria, survive extreme temperatures (60-100°C+).
- The molecular basis for this thermostability remains largely unknown.
Purpose of the Study:
- Investigate amino acid and codon preferences in thermal adaptation.
- Identify molecular markers distinguishing prokaryotic temperature adaptations.
- Elucidate mechanisms contributing to protein thermostability.
Main Methods:
- Comparative proteome analysis of 28 prokaryotic genomes (mesophiles, thermophiles, hyperthermophiles).
- Analysis of amino acid pair ratios (E+K/Q+H).
- Codon usage analysis, focusing on arginine (Arg) codons.
Main Results:
- Hyperthermophiles showed a high E+K/Q+H ratio (>4.5), mesophiles a low ratio (<2.5), and thermophiles intermediate values.
- Thermostable proteins (chaperonins) exhibited higher E+K/Q+H ratios than their proteomes.
- Hyperthermophiles preferentially used AGR codons for Arg, while mesophiles preferred CGN codons.
Conclusions:
- The E+K/Q+H ratio can distinguish between hyperthermophilic, thermophilic, and mesophilic prokaryotes.
- A high percentage of glutamate (E) and lysine (K), coupled with low glutamine (Q) and histidine (H), likely contributes to protein thermostability.
- A preference for AGR codons for Arg is a signature of hyperthermophilic prokaryotes.