【 Seminar Announcement 】
----------------------------------------
Date/Time: March 31, 2014（Mon) Time:16:00-17:00
Place: 3F Seminar room, Nanobiology Building
----------------------------------------
Title："What structural dissection of bacterial flagellar motors in situ
tells us about molecular mechanism and evolution"
Prof. Morgan Beeby
(Department of Life Sciences, Imperial College London)
----- Abstract -----------------------------------------
Understanding how proteins act as nanomachines is of critical importance. An excellent case-study in protein nanomachinery is the bacterial flagellar motor, which both spins the flagellar filament to propel the cell to favourable environments, and self-assembles using an integral "type III secretion system". To study these two mechanisms, we have employed electron cryo-tomography to produce 3-D images of flagellar motors in situ at resolutions sufficient to resolve individual proteins. The foundation of our studies was a comparative imaging study of flagellar motors from a range of phylogenetically diverse bacteria that revealed widespread elaborations upon the 'normal' Salmonella enterica or Escherichia coli motors. This study enabled us to augment our comparative electron cryo-tomography approach with genetic screens and bioinformatics to pinpoint the location of the two energy-transducing proteins involved in type III secretion self-assembly, enabling us to develop a working model on the mechanism of type III secretion. Our studies also revealed variations in the torque-generating components between motors from different species, enabling us to correlate structure with function and hypothesize about evolution of additional complexity seen in some species. In conclusion, electron cryo-tomography enables us to brides scales from the organism to atomic structure of proteins and construct mechanistic hypotheses regarding the function of macromolecular machinery.
--------------------------------------------------------------
----------------------------------------
Date/Time: March 31, 2014（Mon) Time:16:00-17:00
Place: 3F Seminar room, Nanobiology Building
----------------------------------------
Title："What structural dissection of bacterial flagellar motors in situ
tells us about molecular mechanism and evolution"
Prof. Morgan Beeby
(Department of Life Sciences, Imperial College London)
----- Abstract -----------------------------------------
Understanding how proteins act as nanomachines is of critical importance. An excellent case-study in protein nanomachinery is the bacterial flagellar motor, which both spins the flagellar filament to propel the cell to favourable environments, and self-assembles using an integral "type III secretion system". To study these two mechanisms, we have employed electron cryo-tomography to produce 3-D images of flagellar motors in situ at resolutions sufficient to resolve individual proteins. The foundation of our studies was a comparative imaging study of flagellar motors from a range of phylogenetically diverse bacteria that revealed widespread elaborations upon the 'normal' Salmonella enterica or Escherichia coli motors. This study enabled us to augment our comparative electron cryo-tomography approach with genetic screens and bioinformatics to pinpoint the location of the two energy-transducing proteins involved in type III secretion self-assembly, enabling us to develop a working model on the mechanism of type III secretion. Our studies also revealed variations in the torque-generating components between motors from different species, enabling us to correlate structure with function and hypothesize about evolution of additional complexity seen in some species. In conclusion, electron cryo-tomography enables us to brides scales from the organism to atomic structure of proteins and construct mechanistic hypotheses regarding the function of macromolecular machinery.
--------------------------------------------------------------