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Genome sequence of the stramenopile Blastocystis, a human anaerobic parasite

France Denoeud1, Michaël Roussel23, Benjamin Noel1, Ivan Wawrzyniak23, Corinne Da Silva1, Marie Diogon23, Eric Viscogliosi4567, Céline Brochier-Armanet89, Arnaud Couloux1, Julie Poulain1, Béatrice Segurens1, Véronique Anthouard1, Catherine Texier23, Nicolas Blot23, Philippe Poirier23, Geok Choo Ng10, Kevin SW Tan10, François Artiguenave1, Olivier Jaillon1, Jean-Marc Aury1, Frédéric Delbac23, Patrick Wincker1*, Christian P Vivarès23* and Hicham El Alaoui23*

Author Affiliations

1 Genoscope (CEA) and CNRS UMR 8030, Université d'Evry, 2 rue Gaston Crémieux, 91057 Evry, France

2 Clermont Université, Université Blaise Pascal, Laboratoire Microorganismes: Génome et Environnement, BP 10448, F-63000 Clermont-Ferrand, France

3 CNRS, UMR 6023, LMGE, F-63177 Aubière, France

4 Center for Infection and Immunity of Lille, Institut Pasteur de Lille, F-59019 Lille Cedex, France

5 Inserm U1019, F-59000 Lille Cedex, France

6 CNRS UMR 8402, F-59021 Lille Cedex, France

7 University Lille-Nord de France, F-59000 Lille Cedex, France

8 Laboratoire de chimie bactérienne (CNRS UPR9043), Institut de Microbiologie de la Méditerrannée, 31 chemin Joseph Aiguier, 13402 Marseille, France

9 Université de Provence, Aix-Marseille I, 3 place Victor Hugo, 13331 Marseille, France

10 Laboratory of Molecular and Cellular Parasitology, Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 5 Science Drive 2, 117597 Singapore

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Genome Biology 2011, 12:R29  doi:10.1186/gb-2011-12-3-r29

Published: 25 March 2011

Abstract

Background

Blastocystis is a highly prevalent anaerobic eukaryotic parasite of humans and animals that is associated with various gastrointestinal and extraintestinal disorders. Epidemiological studies have identified different subtypes but no one subtype has been definitively correlated with disease.

Results

Here we report the 18.8 Mb genome sequence of a Blastocystis subtype 7 isolate, which is the smallest stramenopile genome sequenced to date. The genome is highly compact and contains intriguing rearrangements. Comparisons with other available stramenopile genomes (plant pathogenic oomycete and diatom genomes) revealed effector proteins potentially involved in the adaptation to the intestinal environment, which were likely acquired via horizontal gene transfer. Moreover, Blastocystis living in anaerobic conditions harbors mitochondria-like organelles. An incomplete oxidative phosphorylation chain, a partial Krebs cycle, amino acid and fatty acid metabolisms and an iron-sulfur cluster assembly are all predicted to occur in these organelles. Predicted secretory proteins possess putative activities that may alter host physiology, such as proteases, protease-inhibitors, immunophilins and glycosyltransferases. This parasite also possesses the enzymatic machinery to tolerate oxidative bursts resulting from its own metabolism or induced by the host immune system.

Conclusions

This study provides insights into the genome architecture of this unusual stramenopile. It also proposes candidate genes with which to study the physiopathology of this parasite and thus may lead to further investigations into Blastocystis-host interactions.