DYNAMIC, MITOTIC-LIKE BEHAVIOR OF A BACTERIAL PROTEIN REQUIRED FOR ACCURATE CHROMOSOME PARTITIONING

The Bacillus subtilis spo0J gene is required for accurate chromosome p artitioning during growth and sporulation. We have characterized the s ubcellular localization of Spo0J protein by immunofluorescence and, in living cells, by use of a spo0J-gfp fusion. We show that the Spo0J pr otein forms discrete stable foci usually located close to the cell pol es. The foci replicate in concert with the initiation of new rounds of DNA replication, after which the daughter foci migrate apart inside t he cell. This migration is independent of cell length extension, and p resumably serves to direct the daughter chromosomes toward opposite Do les of the cell, ready for division. During sporulation, the foci move to the extreme poles of the cell, where they function to position the oriC region of the chromosome ready for polar septation. These observ ations provide strong evidence for the existence of a dynamic, mitotic -like apparatus responsible for chromosome partitioning in bacteria.