An Overexpression Screen of Toxoplasma gondii Rab-GTPases Reveals Distinct Transport Routes to the Micronemes

PLoS Pathogens

Halley Flammer¹  Vernon B. Carruthers¹  Dirk Kamin²  Stefan W. Hell²  Eva Rittweger³  Joanne Heng⁴  Markus Meissner⁴  Katrin Kremer⁴  Jonathan Wilkes⁴  Gordon Langsley⁵  David J. P. Ferguson⁶  Sabine Mahler⁷  Christopher J. Tonkin⁸ 

[1] Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America;Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany;German Cancer Research Center/BioQuant, Heidelberg, Germany;Institute of Infection, Immunity and Inflammation, Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom;Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Institut Cochin, Inserm, U567, CNRS, UMR 8104, Faculté de Médecine Paris V – Hôpital Cochin, Paris, France;Nuffield Department of Pathology, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom;Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Heidelberg, Germany;Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia

关键词: Cellular structures;    organelles;    Apicomplexa;    Immunofluorescence;    Hyperexpression techniques;    Sequence motif analysis;    Parasite replication;    Eukaryota;    Host cells;   

DOI  :  10.1371/journal.ppat.1003213

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The basic organisation of the endomembrane system is conserved in all eukaryotes and comparative genome analyses provides compelling evidence that the endomembrane system of the last common eukaryotic ancestor (LCEA) is complex with many genes required for regulated traffic being present. Although apicomplexan parasites, causative agents of severe human and animal diseases, appear to have only a basic set of trafficking factors such as Rab-GTPases, they evolved unique secretory organelles (micronemes, rhoptries and dense granules) that are sequentially secreted during invasion of the host cell. In order to define the secretory pathway of apicomplexans, we performed an overexpression screen of Rabs in Toxoplasma gondii and identified Rab5A and Rab5C as important regulators of traffic to micronemes and rhoptries. Intriguingly, we found that not all microneme proteins traffic depends on functional Rab5A and Rab5C, indicating the existence of redundant microneme targeting pathways. Using two-colour super-resolution stimulated emission depletion (STED) we verified distinct localisations of independent microneme proteins and demonstrate that micronemal organelles are organised in distinct subsets or subcompartments. Our results suggest that apicomplexan parasites modify classical regulators of the endocytic system to carryout essential parasite-specific roles in the biogenesis of their unique secretory organelles.

【 授权许可】

CC BY