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SUMMARY:LMB Seminar Series - Towards a mechanistic understanding of  cellu
 lar processes by cryo-EM - Gaia Pigino\, Research Group Leader at the MPI-
 CBG
DTSTART:20190527T230000Z
DTEND:20190527T230000Z
UID:TALK122152@talks.cam.ac.uk
CONTACT:72112
DESCRIPTION:Abstract: New cryo-EM technologies enable to investigate prote
 in structures in the native physiological context of the cell. We use thes
 e technologies to study the self-organized assembly of cilia\, ubiquitous 
 organelles of eukaryotic cells.\nAssembly of the cilium requires the rapid
  bidirectional intraflagellar transport (IFT) of building blocks to and fr
 om the site of assembly at its tip. This bidirectional transport is driven
  by the anterograde motor kinesin-2 and the retrograde motor dynein-1b\, w
 hich are both bound to a large complex of 25 IFT adaptor proteins. We have
  recently developed a millisecond resolution 3D correlative light and elec
 tron microscopy (CLEM) approach to show that anterograde and retrograde IF
 T trains use separated microtubule tracks along the microtubule doublets o
 f the cilium (Stepanek & Pigino\, 2016). With this method at hand we showe
 d that the spatial segregation of oppositely directed trains ensures a col
 lision free transport in the cilium. However\, it remained to be explained
  how competition between kinesin and dynein motors\, which are both found 
 on the same anterograde trains\, is avoided. In bidirectional transport sy
 stems in the cell\, other than IFT\, the presence of opposing motors leads
  to periodic stalling and slowing of cargos moving along the microtubule. 
 No such effect occurs in IFT. To address these questions\, we take advanta
 ge of the most advanced technologies in cryo-electron tomography and sub-t
 omogram averaging. After obtaining the 3D structure of IFT train complexes
  in the cilia of intact Chlamydomonas cells\, we showed that a tug-of-war 
 between kinesin-2 and dynein-1b is prevented by loading dynein-1b onto ant
 erograde IFT trains in an inhibited conformation and by positioning it awa
 y from the microtubule track to prevent binding. These findings show how t
 ightly coordinated structural changes mediate the behavior of such a compl
 ex cellular machine.\n
LOCATION:Max Perutz Lecture Theatre\, Medical Research Council (MRC) (MRC 
 Laboratory of Molecular Biol
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