SpoIIDMP-driven peptidoglycan rearrangement is crucial for ribosome translocation into the spore

In a spore-forming bacterium Bacillus subtilis transcription and translation are uncoupled and the translational machinery is located at the cell poles. During sporulation the cell undergoes morphological changes including asymmetric septation and chromosome translocation. However, the fate of translational machinery during sporulation has not been described. Here, using a combination of microscopic assays and mass spectrometry, we are tracking the ribosome localisation during sporulation in B. subtilis WT and mutants. We show that the ribosomes are associated with the asymmetric septum which is a functionally important organelle and that peptidoglycan rearrangement is essential for ribosome packing into the forespore. We also show that the feeding tube channel SpoIIIA-SpoIIQ is not required for the ribosome translocation, but is essential for maintaining the chromosome inside the spore. One-Sentence Summary Movement of ribosomes into the spore of B. subtilis follows chromosome transport and is precisely orchestrated in the cell.