The membrane-bound cell division protein DivlB is localized to the division site in Bacillus subtilis

The cell division gene divlB of Bacillus subtilis is essential for the normal rate of growth and division. The gene product, DivlB, is a membrane-bound protein in which the bulk of the protein (at the C-terminal end) is on the exterior surface of the cell membrane. DivlB is involved in the early stages of septum formation, but its exact role in cell division is unknown. To gain more information about the mode of action of DivlB in septum formation, we determined the location of DivlB within the cell membrane using immunofluorescence. This immunolocalization approach established that DivlB becomes localized to the division site before visible septation and remains localized to this site throughout the division process. Various DivlB immunostaining patterns were observed in immunofluorescence experiments and, together with cell length and nucleoid distance measurements, have allowed us to propose two models to describe DivlB localization during the cell cycle.