title: Visualization of the exocyst complex dynamics at the plasma membrane of Arabidopsis thaliana.
abstract: The exocyst complex, an effector of Rho and Rab GTPases, is believed to function as an exocytotic vesicle tether at the plasma membrane before soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex formation. Exocyst subunits localize to secretory-active regions of the plasma membrane, exemplified by the outer domain of Arabidopsis root epidermal cells. Using variable-angle epifluorescence microscopy, we visualized the dynamics of exocyst subunits at this domain. The subunits colocalized in defined foci at the plasma membrane, distinct from endocytic sites. Exocyst foci were independent of cytoskeleton, although prolonged actin disruption led to changes in exocyst localization. Exocyst foci partially overlapped with vesicles visualized by VAMP721 v-SNARE, but the majority of the foci represent sites without vesicles, as indicated by electron microscopy and drug treatments, supporting the concept of the exocyst functioning as a dynamic particle. We observed a decrease of SEC6-green fluorescent protein foci in an exo70A1 exocyst mutant. Finally, we documented decreased VAMP721 trafficking to the plasma membrane in exo70A1 and exo84b mutants. Our data support the concept that the exocyst-complex subunits dynamically dock and undock at the plasma membrane to create sites primed for vesicle tethering.
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague 6, Czech Republic. fendrych@ueb.cas.cz
authors.forename: Matyás
authors.initials: M
authors.lastname: Fendrych
authors.forename: Lukás
authors.initials: L
authors.lastname: Synek
authors.forename: Tamara
authors.initials: T
authors.lastname: Pecenková
authors.forename: Edita Janková
authors.initials: EJ
authors.lastname: Drdová
authors.forename: Juraj
authors.initials: J
authors.lastname: Sekeres
authors.forename: Riet
authors.initials: R
authors.lastname: de Rycke
authors.forename: Moritz K
authors.initials: MK
authors.lastname: Nowack
authors.forename: Viktor
authors.initials: V
authors.lastname: Zársky
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D003593:Cytoplasm / Q000378:metabolism / Q000648:ultrastructure; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D005089:Exocytosis; D015870:Gene Expression; D008856:Microscopy, Fluorescence; D019441:Plant Epidermis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D021381:Protein Transport; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D022142:Secretory Vesicles / Q000378:metabolism / Q000648:ultrastructure; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D050600:SNARE Proteins; D020691:rab GTP-Binding Proteins