Thursday 31 March; Delft,Dirk Görlich, The permeability barrier of nuclear pore complexes



BN seminar

Location: Room E, F005 (TNW building)

Jaan Männik (BN) will open the ball, followed by Dirk Görlich from the MPI Göttingen (see title and abstract below).

Abstract: The permeability barrier of nuclear pore complexes (NPCs) is  
a passive and yet highly efficient sorting device that controls all  
exchange between nucleus and cytoplasm. It suppresses the flux of  
inert macromolecules > 30 kDa, but also allows rapid passage of even  
very large cargoes, provided these are bound to appropriate nuclear  
transport receptors (NTRs). FG-repeat domains bind NTRs during  
facilitated NPC passage and constitute the crucial elements of this  
barrier. They are essential for viability and comprise up to 50 repeat  
units. Each unit contains a hydrophobic cluster, typically of the  
sequence FG, FxFG or GLFG, surrounded by more hydrophilic spacer  
sequences. We observed that FG-repeat domains form FG-hydrogels. These  
gels are fascinating materials that display permeability properties  
very similar to those of authentic NPCs, allowing an up to 20 000-fold  
faster entry of large NTR–cargo complexes as compared to the cargoes  
alone. While supporting massive importin- or exportin-mediated cargo  
influx, such gels remain firm barriers towards inert objects that lack  
nuclear transport signals. This indicates that FG-hydrogels reseal  
immediately behind a translocating species and thus possesses "self-
healing" properties. The presentation will further address the  
following questions: What is the molecular and structural basis of  
barrier formation? Why do the meshes of the barrier open at least 100  
times faster in the immediate vicinity of a nuclear transport receptor  
than elsewhere in the gel? How do FG repeat domains behave on a  
nanoscopic scale, i.e. in authentic NPCs?