The genus Paulinella represents a rare, independent case of primary endosymbiosis, providing a unique system to study the early stages of organelle evolution. Here, we expand current understanding of...

Under nutrient limitation or stress, ribosome hibernation factors inactivate and protect ribosomes. Although ribosome hibernation plays an important role in microbes, we lack a complete understanding of this process in archaea. Here, we identify a family of hibernation factors, which we designate as single ribosomal subunit inhibitors (SriA- SriD), from the methanogenic archaeon Methanosarcina acetivorans . All four sri genes are encoded in an operon and each Sri protein inhibits protein synthesis in vitro . Deletion of sri genes in M. acetivorans impaired growth recovery after prolonged stationary phase and also led to depletion of the small ribosomal subunit. Cryo-EM structures show that Sri proteins bind to the ribosome in tandem and form conserved protein-protein interfaces. Sri is broadly distributed across archaeal phyla and sri genes frequently co-occur. Together, these findings establish Sri proteins as a distinct group of hibernation factors that protect ribosomes during dormancy and expand our understanding of ribosome hibernation in archaea. ### Competing Interest Statement The authors have declared no competing interest. U.S. National Science Foundation, https://ror.org/021nxhr62, CHE-2002182 National Institutes of Health, https://ror.org/01cwqze88, 5T32GM132022 Life Sciences Research Foundation, https://ror.org/0195dxj21 Arnold and Mabel Beckman Foundation, https://ror.org/05avmtm72 Alfred P. Sloan Foundation, https://ror.org/052csg198 Simons Foundation, https://ror.org/01cmst727 David and Lucile Packard Foundation, https://ror.org/032atxq54 Chan Zuckerberg Biohub San Francisco

Tighter federal borrowing limits may deepen inequities, especially for students from underrepresented backgrounds.

Scientists have identified tubulin structures in primitive Asgard archea that may have been the precursor of our own cellular skeletons.

Abstract. Lateral gene transfer is a major evolutionary process in Bacteria and Archaea. Despite its importance, lateral gene transfer quantification in na

In a hot spring at Yellowstone National Park, a microbe does something that life shouldn’t be able to do: It breathes oxygen and sulfur at the same time.

Screening shotgun-sequencing data from ancient humans covering 37,000 years of Eurasian history uncovers the widespread presence of ancient bacterial, viral and parasite DNA and zoonotic pathogens coi...