Combing Transcriptomes for Secrets of Deep-Sea Survival: Environmental Diversity Drives Patterns of Protein Evolution

Area of Science:

• Marine Biology
• Molecular Evolution
• Biochemistry

Background:

• Ctenophores inhabit wide temperature and pressure ranges.
• Independent adaptations in ctenophore lineages offer insights into protein evolution.
• Phylum Ctenophora provides a model for studying adaptation to extreme environments.

Purpose of the Study:

• To investigate protein adaptation to extreme oceanic conditions using a comparative phylogenetic approach.
• To identify specific amino acid sites involved in adaptation to depth and temperature in ctenophores.

Main Methods:

• Phylogenetically-informed comparative sequence analysis of four essential metabolic enzymes.
• Analysis across environmental gradients of habitat depth and temperature.
• Identification of amino acid sites showing convergent adaptation.

Main Results:

• 46 amino acid sites linked to depth adaptation, 59 to temperature adaptation, and 56 to both.
• Adaptive sites frequently found near Rossmann fold motifs and in solvent-exposed regions.
• Convergent amino acid substitutions suggest adaptation to hydrostatic pressure and temperature.

Conclusions:

• Phylogenetic comparison of ctenophore enzymes reveals convergent protein adaptation to extreme environments.
• Hydrophobic effects and ligand binding likely mediate enzyme function under varying pressure and temperature.
• Identified adaptive sites provide targets for future experimental validation via mutagenesis.