title: N-ethylmaleimide-sensitive factor is required to organize functional exocytotic microdomains in paramecium.
abstract: In exocytosis, secretory granules contact plasma membrane at sites where microdomains can be observed, which are sometimes marked by intramembranous particle arrays. Such arrays are particularly obvious when membrane fusion is frozen at a subterminal stage, e.g., in neuromuscular junctions and ciliate exocytotic sites. In Paramecium, a genetic approach has shown that the "rosettes" of intramembranous particles are essential for stimulated exocytosis of secretory granules, the trichocysts. The identification of two genes encoding the N-ethylmaleimide-sensitive factor (NSF), a chaperone ATPase involved in organelle docking, prompted us to analyze its potential role in trichocyst exocytosis using a gene-silencing strategy. Here we show that NSF deprivation strongly interferes with rosette assembly but does not disturb the functioning of exocytotic sites already formed. We conclude that rosette organization involves ubiquitous partners of the fusion machinery and discuss where NSF could intervene in this mechanism.
authors.affiliation: Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette Cedex, France.
authors.forename: Marine
authors.initials: M
authors.lastname: Froissard
authors.forename: Roland
authors.initials: R
authors.lastname: Kissmehl
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Dedieu
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Gulik-Krzywicki
authors.forename: Helmut
authors.initials: H
authors.lastname: Plattner
authors.forename: Jean
authors.initials: J
authors.lastname: Cohen
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology*; D020868:Gene Silencing; D008561:Membrane Fusion / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D052066:N-Ethylmaleimide-Sensitive Proteins; D010247:Paramecium / Q000235:genetics*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D033921:Vesicular Transport Proteins
chemical_list: D002352:Carrier Proteins; D015800:Protozoan Proteins; D033921:Vesicular Transport Proteins; D052066:N-Ethylmaleimide-Sensitive Proteins