biorxiv.org
A family of archaeal hibernation factors that bind in tandem and protect ribosomes in dormant cells
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
