title: Dd-Alix, a conserved endosome-associated protein, controls Dictyostelium development.
abstract: We have characterized the Dictyostelium homolog of the mammalian protein Alix. Dd-Alix is encoded by a single gene and is expressed during vegetative growth and multicellular development. We showed that the alx null strain fails to complete its developmental program. Past the tight aggregate stage, morphogenesis is impaired, leading to markedly aberrant structures containing vacuolated and undifferentiated cells but no mature spores. The developmental defect is cell-autonomous as most cells remain of the PstB type even when mixed with wild-type cells. Complementation analysis with different Alix constructs allowed the identification of a 101-residue stretch containing a coiled-coil domain essential for Alix function. In addition, we showed that the protein associates in part with vesicular structures and that its distribution on a Percoll gradient overlaps that of the endocytic marker Vamp7. Dd-Alix also co-localizes with Dd-Vps32. In view of our data, and given the role of Vps32 proteins in membrane protein sorting and multivesicular body formation in yeast and mammals, we hypothesize that the developmental defects of the alx null strain result from abnormal trafficking of cell-surface receptors.
authors.affiliation: The Laboratoire de Biochimie et Biophysique des Systèmes Intégrés (UMR 5092 CNRS-CEA-UJF), DRDC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: Sara
authors.initials: S
authors.lastname: Mattei
authors.forename: W Jonathan
authors.initials: WJ
authors.lastname: Ryves
authors.forename: Béatrice
authors.initials: B
authors.lastname: Blot
authors.forename: Rémy
authors.initials: R
authors.lastname: Sadoul
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Harwood
authors.forename: Michel
authors.initials: M
authors.lastname: Satre
authors.forename: Gérard
authors.initials: G
authors.lastname: Klein
authors.forename: Laurence
authors.initials: L
authors.lastname: Aubry
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019921:Biotinylation; D017124:Conserved Sequence; D004023:Dictyostelium / Q000166:cytology / Q000254:growth & development*; D011992:Endosomes / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008322:Mammals; D008969:Molecular Sequence Data; D010957:Plasmids; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D015800:Protozoan Proteins