| Talk title | Using images to understand structure, function and dynamics of Type VI secretion systems |
| Speaker | Prof. Marek Basler Tenure Track Assistant Professor, Biozentrum, University of Basel, Basel, Switzerland |
| Date & Time | 24 April 2017 (Monday) 10:30-11:30 |
| Venue | Room G004, E12 Building (University of Macau) |
| Abstract | The bacterial Type VI secretion system (T6SS) is a large dynamic organelle that is functionally analogous to contractile tails of bacteriophages. Gram-negative bacteria use T6SS to inhibit adjacent cells via translocation of toxic effector proteins and thus T6SS often plays an important role in bacterial pathogenesis and ecology. T6SS assembles from three major parts: a membrane complex that spans inner and outer membrane, a baseplate, and a sheath-tube polymer. Time-lapse fluorescence light microscopy revealed that T6SS sheath powers the secretion by cycling between assembly, quick contraction, disassembly and re-assembly. I will present the latest update on the structure of T6SS solved by cryo-electron microscopy and the implications for T6SS dynamics and assembly. I will discuss mechanisms of effector delivery and function in various T6SS+ organisms. I will show that secreted proteins are efficiently exchanged among by-standing cells within minutes of initial cell-cell contact and can be subsequently reused to form a functional T6SS assembly. I will provide an evidence that certain bacteria are able to subcellularly localize T6SS assembly to aim at neighboring cells and show that this increases efficiency of effector translocation to target cells.
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