UC Santa Cruz

Ribosomes are essential macromolecules that convert mRNA to polypeptides and functional proteins. Ribosomes can be regulated by multiple mechanisms, including limiting the biogenesis of ribosomal subunits, sequestering 70S ribosomes, dimerizing 70S complexes into translationally inactive 100S ribosome, and “silencing” the 50S subunit to prevent the assembly of active 70S ribosomes. In this review, we focus on the protein that carries out ribosomal silencing, called ribosomal silencing factor S (RsfS), that has been shown in multiple species to bind to the L14 ribosomal protein in the 50S subunit and prevent 50S-to-30S subunit joining. RsfS is a highly conserved small protein found across most bacterial species and in eukaryotes. The direct target of RsfS, L14 (RplN), is one of the most conserved ribosomal proteins. RsfS has been primarily studied for binding interactions with L14 and the downstream effects of preventing 70S ribosome assembly. rsfS null mutants exhibit defects in in vitro (stationary phase, biofilm, growth, nutrient limitation, oxidative stress) and in vivo (macrophage and murine models) conditions in several bacterial species. However, other topics remain underexplored, highlighting areas for future study such as regulation of RsfS and L14 expression, what factors dictate ribosomal interactions, roles in antibiotic tolerance, and whether RsfS has additional physiological roles.