Biogenesis of the inner membrane complex is dependent on vesicular transport by the alveolate specific GTPase Rab11B

• Published in: PLoS pathogens 2010-07, Vol.6 (7), p.e1001029-e1001029
• Main Authors: Agop-Nersesian, Carolina, Egarter, Saskia, Langsley, Gordon, Foth, Bernardo J, Ferguson, David J P, Meissner, Markus
• Format: Article
• Language: English
• Subjects: Alveolata; Alveolata - growth & development; Alveolata - metabolism; Alveolates; Apicomplexa; Biological Transport; Biosynthesis; Cell Biology; Cell Biology/Cell Growth and Division; Cell Biology/Morphogenesis and Cell Biology; Cell division; Cells, Cultured; Cytoplasmic Vesicles - metabolism; Defects; Experiments; Fibroblasts - parasitology; Genetic aspects; Golgi Apparatus - metabolism; GTP Phosphohydrolases; Guanosine triphosphatase; Humans; Infectious Diseases/Protozoal Infections; Microorganisms; Microtubules; Molecular Biology/Molecular Evolution; Motility; Parasites; Phylogenetics; Properties; Proteins; Protozoan Proteins; rab GTP-Binding Proteins - metabolism; Toxoplasma; Toxoplasma gondii; Toxoplasmosis
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1001029

Apicomplexan parasites belong to a recently recognised group of protozoa referred to as Alveolata. These protists contain membranous sacs (alveoli) beneath the plasma membrane, termed the Inner Membrane Complex (IMC) in the case of Apicomplexa. During parasite replication the IMC is formed de novo within the mother cell in a process described as internal budding. We hypothesized that an alveolate specific factor is involved in the specific transport of vesicles from the Golgi to the IMC and identified the small GTPase Rab11B as an alveolate specific Rab-GTPase that localises to the growing end of the IMC during replication of Toxoplasma gondii. Conditional interference with Rab11B function leads to a profound defect in IMC biogenesis, indicating that Rab11B is required for the transport of Golgi derived vesicles to the nascent IMC of the daughter cell. Curiously, a block in IMC biogenesis did not affect formation of sub-pellicular microtubules, indicating that IMC biogenesis and formation of sub-pellicular microtubules is not mechanistically linked. We propose a model where Rab11B specifically transports vesicles derived from the Golgi to the immature IMC of the growing daughter parasites.