The interplay between ribosomal anti-association factors during ribosome maturation

Ribosome biogenesis involves a series of steps, starting from the folding and modification of ribosomal RNA (rRNA) to the assembly of ribosomal proteins and their incorporation into rRNA. Various biogenesis factors play crucial roles in guiding ribosome maturation. Disruptions in these factors result in significant growth impairments and the accumulation of immature ribosomal subunits1. Under such adverse conditions, bacteria may employ stress factors associated with ribosomes to modulate ribosome assembly. The ribosomal maturation factor M (RimM) is necessary for the maturation of the 30S small ribosomal subunit2. Deletion of RimM leads to a decrease in growth rate and a decline in translation efficiency3. Despite this, the gradual recovery of the bacterial phenotype indicates the presence of a reactivation mechanism to restore translation. Ribosomal silencing factor S (RsfS)4 plays a key role in suppressing protein synthesis by binding to the 50S ribosomal subunit, thereby preventing the formation of 70S ribosomes5. This action potentially shields mature 50S subunits from associating with immature 30S subunits. Here, we show close association between initiation factor IF3 and RsfS, and their capabilities on modulating translation and ribosome maturation using a combination of biochemical and structural studies.