A conserved archaeal protein with evolutionary links to bacterial ribosome hibernation and eukaryotic energy sensing.

AHA, a conserved archaeal ribosome-associated protein, supports ribosome hibernation and shares evolutionary links with bacterial HPF and eukaryotic AMPKγ.

• Why it matters: Understanding archaeal ribosome hibernation fills a significant knowledge gap, as it is less characterized compared to bacteria and eukaryotes, and reveals evolutionary connections across domains.
• What they did: Using cryoEM of archaeal lysates, researchers identified AHA, a two-module protein that binds ribosomes and occludes key functional sites; they also performed phylogenetic analyses and observed AMP binding to AHA.
• The result: Loss of AHA impairs cell viability and growth reentry, and findings suggest that archaeal hibernation factors are evolutionarily linked to bacterial HPF and eukaryotic energy sensors, indicating a shared ancestral origin.