The Min system in rod-shaped bacteria restricts improper assembly of the division septum. In Escherichia coli, the Min system localizes to the cell poles, but in Bacillus subtilis, it is recruited to nascent cell division sites at mid-cell to prevent aberrant septation events immediately adjacent to a constricting septum. How does the cell spatially and temporally restrict the inhibitory activity of the Min system so that it does not interfere with normal cell division? This image reveals (using a super-resolution fluorescence microscopy technique called SIM) that the cell division protein DivIVA (green), which preferentially localizes to negatively curved membranes (red) and is responsible for recruitment of the Min system, localizes as double rings on either side of actively constricting septa and remains associated with mature septa after completion of cell division.
In the related article, the authors propose that DivIVA interprets membrane invagination as evidence of cell division and localizes to mid-cell only after the onset of membrane constriction. Additionally, the formation of two ring-shaped platforms on either side of the septum reveals a mechanism by which the inhibitory activity of the Min system is held away from a newly forming septum, while simultaneously inhibiting aberrant septation at sites immediately adjacent to mid-cell.
Cellular architecture mediates DivIVA ultrastructure and regulates min activity in Bacillus subtilis
Prahathees Eswaramoorthya, Marcella L. Erbb, James A. Gregoryb, Jared Silvermanc, Kit Poglianob, Joe Poglianob, and Kumaran S. Ramamurthia. mBio 2(6):e00257–11, 2011.
aLaboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
bDivision of Biological Sciences, University of California at San Diego, La Jolla, California, USA
cCubist Pharmaceuticals, Lexington, Massachusetts, USA