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Life Sciences seminar by Dr Erdem Karatekin, Yale
:“Protein sub-cellular localization and membrane fission in bacteria during endospore formation”
Bacteria rely on membrane fission for division and endospore formation. A protein called FisB catalyzes membrane fission during sporulation, but the molecular basis is unclear as FisB is incapable of remodeling membranes on its own. Sporulation initiates with an asymmetric division that generates a large mother cell and a small forespore that contains only 1/4 of its complete genome. As the mother cell membranes engulf the forespore, a DNA translocase pumps the rest of the chromosome into the small forespore compartment. When the engulfing membranes undergo fission at the cell pole, the forespore is released into the mother cell cytoplasm.
I will discuss how FisB localizes to the highly curved membrane neck that eventually gets cut, relying on homo-oligomerization and trans interactions that bridge membranes, but surprisingly, not on curvature sensing. Inflation of the forespore due to DNA-translocation additionally promotes FisB accumulation at the fission site. Finally, we find that FisB accumulation and forespore inflation are both required for efficient membrane fission. Overall, our data indicate that DNA-translocation has a previously unappreciated second function in energizing FisB-mediated membrane fission under energy-limited conditions.