Proteomic signatures of cold adaptation and sponge host adaptation in marine Archaea

Amino acid compositional indices showed no detectable cold-adaptation signature in 3 Marine Group I (MG-I; Thaumarchaeota) metagenome-assembled genomes from the Western Arctic Ocean, but did reveal sponge-associated proteomic signatures.

• Why it matters: Temperature-linked protein chemistry may enable cold-adaptation detection, yet it is unknown whether Bacteria-derived amino-acid indices work for Archaea common in cold marine settings.
• What they did: The study computed six amino-acid compositional indices across global protein families for 142 MG-I and 146 Euryarchaeota genomes from BV-BRC, plus 3 Western Arctic MG-I MAGs, and compared index patterns to phylogeny and habitat.
• The result: Cold adaptation was not detected; instead, MG-I indices differed by MG-I phylogenetic group and by freshwater versus marine genomes, while 19 sponge-associated MG-I MAGs had higher arginine-to-lysine ratios and distinct amino-acid, codon, and GC-content patterns.

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