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Division site selection protein DivIVA of Bacillus subtilis has a second distinct function in chromosome segregation
H B Thomaides1, M Freeman, M El Karoui
1Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
Abstract:
DivIVA is a coiled-coil, tropomyosin-like protein of Gram-positive bacteria. Previous work showed that this protein is targeted to division sites and retained at the cell poles after division. In vegetative cells, DivIVA sequesters the MinCD division inhibitor to the cell poles, thereby helping to direct cell division to the correct midcell site. We now show that DivIVA has a second, quite separate role in sporulating cells of Bacillus subtilis. It again acts at the cell pole but in this case interacts with the chromosome segregation machinery to help position the oriC region of the chromosome at the cell pole, in preparation for polar division. We isolated mutations in divIVA that separate the protein's role in sporulation from its vegetative function in cell division. DivIVA therefore appears to be a bifunctional protein with distinct roles in division-site selection and chromosome segregation.