Required and sufficient for dimerization of active 70S ribosomes into 100S ribosomes. 110S ribosomes are probably translationally inactive and may serve as a reservoir of easily reactivated ribosomes when necessary in the cell. Also reduces the translation efficiency of a small number of genes. Unlike E.coli, 100S ribosomes are present during exponential growth and decrease during stationary phase. This strain produces 30% fewer 100S ribosomes than strain N315 and RN4200 under the same growth conditions (PubMed:27001516). Interacts with 100S ribosomes during exponential growth, as 100S ribosomes decrease (after 28 hours) also found associated with 30s and 50S subunits. The C-terminus (residues 101-190) is required for ribosome-binding; deletion of the last 42 residues partially decreases ribosome-binding. 400-fold decreased cell survival in long-term growth, effects are more pronounced in minimal medium. No visible formation of 100S ribosomes, rapid degradation of ribosomes once cells have reached stationary phase. Belongs to the HPF/YfiA ribosome-associated protein family. Long HPF subfamily.