IBIP seminar

Thursday, October 20, 2016

Exocyst complex and the secretory pathway logistics in plants

Viktor Zarsky
Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic

In the context of endomembrane trafficking, tethering factors act as a molecular bridges that provide a first recognition/interaction interface between arriving vesicles and their target membrane. Exocyst is an octameric vesicle tethering protein complex playing an important roles in targeting and docking of vesicles to the plasma membrane during exocytosis and in membrane proteins recycling. Exocyst was discovered in yeast as an effector of Rab and Rho GTPases and in most eukaryotes including plants is required for targeting of the secretory pathway – i.e. for cell polarity and cell morphogenesis. However, we also unexpectedly found that a version of the exocyst is involved in an autophagy-related membrane traffic to the vacuole via a pathway not involving the Golgi apparatus. Multiplicity of EXO70 paralogs encoded by land plant genomes is a very peculiar feature obviously linked not only to different cells specific function, but also linked to specific secretory processes within the same one cell. Specific exocyst complexes (based on distinct EXO70 isoforms) possibly have multiple roles in land plants life. Exocyst in plants is implied in regulation of cytokinesis, recycling of PM proteins (incl. PINs), cell wall biogenesis (e.g. seed coat formation), pollen tube development and fertilization, stomata regulation, stress responses and biotic interactions including defense against pathogens; in its autophagy engagement exocyst is participating in the anthocyanins vacuolar accumulation and biotic interactions. Exocyst complexes dynamics in plants might contribute significantly to the endomembrane transport pathways coordination.
Acknowledgement: this work is supported by the CSF/GACR project 15-14886S.

Contact : Doan Luu

Contacts IBIP :
Sabine Zimmermann
Alexandre Martiniere
Christine Granier
Chantal Baracco