Disassembly of the Staphylococcus aureus hibernating 100S ribosome by an evolutionarily conserved GTPase

Significance Bacterial protein synthesis requires the assembly of the 30S and 50S ribosomal subunits on mRNA to form the translationally competent 70S complex. Nontranslating 70S ribosomes homodimerize into a translationally inactive 100S ribosome to promote bacterial survival. The conversion between the 70S and 100S complexes is reversible, but the disassembly pathway of the 100S ribosome is unknown. We show that an evolutionarily conserved GTPase (HflX) splits the Staphylococcus aureus 100S ribosome in a GTP-dependent fashion; the abundance of 100S is influenced by the opposing functions of the dimerizing factor (HPF) and HflX, whose actions are coregulated by the heat stress response and (p)ppGpp-mediated stringent control. These findings provide insights into the crosstalk between the 100S ribosome biogenesis and stress response.