Structural clustering across the tree of life reveals candidate Asgard-eukaryote homologs and a shared expansion of solenoids

Structural clustering of 1.89 million AFESM structural clusters finds 133 clusters shared exclusively by Asgard archaea and eukaryotes, including 73 lacking any match to an ESP catalogue.

• Why it matters: Sequence divergence limits deep homology detection, so family-level structural profiling is needed to expand the repertoire of eukaryotic signature proteins beyond individual Asgard proteins.
• What they did: The study profiled AFESM’s taxonomic composition across 1.89 million structural clusters from genomes and metagenomes, comparing clusters restricted to Asgard versus other archaea and identifying Asgard–eukaryote-exclusive clusters.
• The result: Asgard-only clusters were nearly twice as likely to contain eukaryotic proteins, and beta-solenoids were enriched in Asgard and eukaryotic proteomes, supporting an expansion before eukaryogenesis.