title: Identification of regions within the Legionella pneumophila VipA effector protein involved in actin binding and polymerization and in interference with eukaryotic organelle trafficking.
abstract: The Legionella pneumophila effector protein VipA is an actin nucleator that co-localizes with actin filaments and early endosomes in infected macrophages and which interferes with organelle trafficking when expressed in yeast. To identify the regions of VipA involved in its subcellular localization and functions, we ectopically expressed specific VipA mutant proteins in eukaryotic cells. This indicated that the characteristic punctate distribution of VipA depends on its NH2 -terminal (amino acid residues 1-133) and central coiled-coil (amino acid residues 133-206) regions, and suggested a role for the COOH-terminal (amino acid residues 206-339) region in association with actin filaments and for the NH2 -terminal in co-localization with early endosomes. Co-immunoprecipitation and in vitro assays showed that the COOH-terminal region of VipA is necessary and sufficient to mediate actin binding, and is essential but insufficient to induce microfilament formation. Assays in yeast revealed that the NH2 and the COOH-terminal regions, and possibly an NPY motif within the NH2 region of VipA, are necessary for interference with organelle trafficking. Overall, this suggests that subversion of eukaryotic vesicular trafficking by VipA involves both its ability to associate with early endosomes via its NH2 -terminal region and its capacity to bind and polymerize actin through its COOH-terminal region.
authors.affiliation: UCIBIO, REQUIMTE, Faculdade de Ciências e Tecnologia, Departamento de Ciências da Vida, Universidade NOVA de Lisboa, Caparica, Portugal.
authors.forename: Joana N
authors.initials: JN
authors.lastname: Bugalhão
authors.affiliation: UCIBIO, REQUIMTE, Faculdade de Ciências e Tecnologia, Departamento de Ciências da Vida, Universidade NOVA de Lisboa, Caparica, Portugal.|Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Oeiras, Portugal.
authors.forename: Luís Jaime
authors.initials: LJ
authors.lastname: Mota
authors.affiliation: UCIBIO, REQUIMTE, Faculdade de Ciências e Tecnologia, Departamento de Ciências da Vida, Universidade NOVA de Lisboa, Caparica, Portugal.|Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Oeiras, Portugal.
authors.forename: Irina S
authors.initials: IS
authors.lastname: Franco
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D016466:CHO Cells; D002460:Cell Line; D003412:Cricetulus; D011992:Endosomes / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D049452:Green Fluorescent Proteins; D016952:Legionella pneumophila / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000382:microbiology; D015388:Organelles / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000378:metabolism
chemical_list: D000199:Actins; D001426:Bacterial Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins
keywords: Actin; Legionella pneumophila; effector; type IV secretion system; vesicle trafficking