title: Epiplasmins and epiplasm in paramecium: the building of a submembraneous cytoskeleton.
abstract: In ciliates, basal bodies and associated appendages are bound to a submembrane cytoskeleton. In Paramecium, this cytoskeleton takes the form of a thin dense layer, the epiplasm, segmented into regular territories, the units where basal bodies are inserted. Epiplasmins, the main component of the epiplasm, constitute a large family of 51 proteins distributed in 5 phylogenetic groups, each characterized by a specific molecular design. By GFP-tagging, we analyzed their differential localisation and role in epiplasm building and demonstrated that: 1) The epiplasmins display a low turnover, in agreement with the maintenance of an epiplasm layer throughout the cell cycle; 2) Regionalisation of proteins from different groups allows us to define rim, core, ring and basal body epiplasmins in the interphase cell; 3) Their dynamics allows definition of early and late epiplasmins, detected early versus late in the duplication process of the units. Epiplasmins from each group exhibit a specific combination of properties. Core and rim epiplasmins are required to build a unit; ring and basal body epiplasmins seem more dispensable, suggesting that they are not required for basal body docking. We propose a model of epiplasm unit assembly highlighting its implication in structural heredity in agreement with the evolutionary history of epiplasmins.
authors.affiliation: Dynamique cellulaire chez la Paramécie, CNRS, Centre de Génétique Moléculaire, UPR3404, Avenue de la Terrasse, F-91198 Gif-sur-Yvette; Université Paris-Sud, F-91405 Orsay, France. anne.aubusson@cgm.cnrs-gif.fr
authors.forename: Anne
authors.initials: A
authors.lastname: Aubusson-Fleury
authors.forename: Geneviève
authors.initials: G
authors.lastname: Bricheux
authors.forename: Raghida
authors.initials: R
authors.lastname: Damaj
authors.forename: Michel
authors.initials: M
authors.lastname: Lemullois
authors.forename: Gérard
authors.initials: G
authors.lastname: Coffe
authors.forename: Florence
authors.initials: F
authors.lastname: Donnadieu
authors.forename: France
authors.initials: F
authors.lastname: Koll
authors.forename: Bernard
authors.initials: B
authors.lastname: Viguès
authors.forename: Philippe
authors.initials: P
authors.lastname: Bouchard
mesh_terms: D002453:Cell Cycle; D003599:Cytoskeleton / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010247:Paramecium / Q000145:classification / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism*; D010802:Phylogeny; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D015800:Protozoan Proteins
keywords: Basal body docking; cell morphogenesis; ciliates.; ciliogenesis; structural heredity; transition zone