"Towards structural insight into the endocytic TPLATE Adaptor Complex"

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Thursday 07 March 2019, 11:00 - 12:30

 
ABSTRACT

The plasma membrane (PM) contains a wide range of receptors, channels and other integral membrane proteins by which the plant cell communicates with the outside world. Modulation of signalling pathways as well as nutrient uptake requires control over the PM proteome. While anterograde (secretory) trafficking deposits PM proteins, their removal depends on retrograde transport by endocytosis, in which PM material and extracellular ligands are internalized.

Clathrin-mediated endocytosis (CME), defined by the involvement of the scaffold protein clathrin, forming a cage around the invaginating membrane, is the predominant endocytic pathway in eukaryotes. Initiation of CME relies on adaptor protein complexes, which precisely select the cargo, recruit the clathrin cage and facilitate membrane curvature.

The identification of the TPLATE complex (TPC), an evolutionary ancient adaptor module which is lost in the lineage leading to animal and fungal cells, as an essential player for CME in plants challenged the general belief that CME is mechanistically conserved in eukaryotes.

A combination of live cell imaging, yeast co-interaction assays, proximity biotinylation, cross-linking mass spectrometry, co-evolution analysis, recombinant protein production and lipid binding assays is employed to generate a structural model of the TPC and to reveal how it interacts with membranes.

Initial modeling of the TPC shows that it shares many features with evolutionary conserved adaptor complexes, but that it also has distinct differences. All data currently points to the TPC being a hexameric core complex which associates with its two peripheral subunits prior to being recruited to the PM. Moreover, membrane interaction and in vivo localization suggests that similar to the AP-2 adaptor complex, TPC undergoes a conformational change during its PM recruitment. Fundamental insight into this essential complex will allow to understand and modulate cargo internalization to control for example nutrient uptake or defense signaling. It will also allow to develop assays for chemical interference leading to novel herbicide discovery.

Location Jozef Schell Seminar Room
Contact Prof Daniël Van Damme
VIB-UGent Center for Plant Systems Biology
Ghent
BELGIUM