Previous Seminars

Additional ICaMB Seminar - Dr Susan Schlimpert

  • Venue: Baddiley Clark Building Seminar Room
  • Start: Thu, 29 Sep 2016 16:00:00 BST
  • End: Thu, 29 Sep 2016 17:00:00 BST

During the reproductive phase, a synchronous cell division event leads to the deposition of a ladder-like array of regularly spaced FtsZ-rings along the sporogenic hyphae of Streptomycetes within a short time. Among the regulatory genes identified to be central to developmentally-controlled cell division is the transcription factor WhiH, which controls an operon of two genes encoding dynamin‐like proteins (DynAB). Dynamin-like proteins are large GTPases that play critical roles in diverse cellular processes in eukaryotes that require membrane fusion or fission. Although bacterial dynamin-like proteins have been partially characterized, their precise function in bacteria has remained poorly understood. Interestingly, in Streptomyces, the disruption of dynAB leads to the creation of long spore compartments containing more than one copy of the chromosome as well as to the formation of incomplete division septa, indicating that the dynamins are required for normal sporulation septation. Using time-lapse fluorescence microscopy, we found that DynAB co-localize with cytokinetic FtsZ rings and are recruited to the future division septum in an FtsZ-dependent manner. Kymograph analyses of fluorescently labelled FtsZ indicate that initial placement of FtsZ rings along the sporogenic hyphae is normal in DdynAB mutant cells but the absence of DynAB significantly affects the persistence of these early FtsZ rings which can cause the disassembly of FtsZ rings and leads to irregular sporulation septation or incomplete constriction of hyphal fragments. Moreover, two-hybrid studies and protein co-purification experiments suggest that the dynamins directly interact with the cell division machinery. Taken together our data demonstrate a novel function of dynamin-like proteins in bacteria. DynA and DynB stabilize pre-formed FtsZ rings at the cytoplasmic membrane and thereby promote coordinated constriction and septum formation during sporulation-specific cell division in Streptomyces.

 

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