Role of the sarcin-ricin loop of 23S rRNA in biogenesis of the 50S ribosomal subunit

In this work, we show that 23S rRNA lacking the SRL can be efficiently reconstituted into 50S subunits, which exhibit full peptidyl transferase (PT) activity. Using cryo-EM and proteomic methods, we also further characterize affinity-purified SRL particles isolated from cells. Collectively, these data suggest that the SRL is needed to promote the dissociation of several AFs during 50S subunit biogenesis in the cell.