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A mitochondrial carrier transports glycolytic intermediates to link cytosolic and mitochondrial glycolysis in the human gut parasite Blastocystis.

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Abstract

Stramenopiles form a clade of diverse eukaryotic organisms, including multicellular algae, the fish and plant pathogenic oomycetes, such as the potato blight Phytophthora, and the human intestinal protozoan Blastocystis. In most eukaryotes, glycolysis is a strictly cytosolic metabolic pathway that converts glucose to pyruvate, resulting in the production of NADH and ATP (Adenosine triphosphate). In contrast, stramenopiles have a branched glycolysis in which the enzymes of the pay-off phase are located in both the cytosol and the mitochondrial matrix. Here, we identify a mitochondrial carrier in Blastocystis that can transport glycolytic intermediates, such as dihydroxyacetone phosphate and glyceraldehyde-3-phosphate, across the mitochondrial inner membrane, linking the cytosolic and mitochondrial branches of glycolysis. Comparative analyses with the phylogenetically related human mitochondrial oxoglutarate carrier (SLC25A11) and dicarboxylate carrier (SLC25A10) show that the glycolytic intermediate carrier has lost its ability to transport the canonical substrates malate and oxoglutarate. Blastocystis lacks several key components of oxidative phosphorylation required for the generation of mitochondrial ATP, such as complexes III and IV, ATP synthase, and ADP/ATP carriers. The presence of the glycolytic pay-off phase in the mitochondrial matrix generates ATP, which powers energy-requiring processes, such as macromolecular synthesis, as well as NADH, used by mitochondrial complex I to generate a proton motive force to drive the import of proteins and molecules. Given its unique substrate specificity and central role in carbon and energy metabolism, the carrier for glycolytic intermediates identified here represents a specific drug and pesticide target against stramenopile pathogens, which are of great economic importance.

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Peer reviewed: True


Acknowledgements: MSK and ACK were supported by grant MC_UU_00028/2 of the UK Medical Research Council to ERSK, and EP and MRT were supported by Norwegian Research Council grant 301170 to MvdG. We thank Dr. Shane Palmer (MRC Mitochondrial Biology Unit) for carrying out large-scale fermentations in this project, Drs. Denis Lacabanne, Sotiria Tavoulari, Camila Cimadamore-Werthein, and Pavel Dolezal for constructive comments on the manuscript, and Associate Professor Kevin SW Tan for the ST7-B Blastocystis culture.

Keywords

Blastocystis, E. coli, S. cerevisiae, SLC25 mitochondrial carrier family, biochemistry, chemical biology, evolutionary biology, human, missing transport link, protists, thermostability shift assays, transport assays, Blastocystis, Glycolysis, Humans, Mitochondria, Cytosol, Biological Transport, Protozoan Proteins

Journal Title

eLife

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Journal ISSN

2050-084X

Volume Title

13

Publisher

eLife Sciences Publications, Ltd
Sponsorship
Norges Forskningsråd (301170)
Medical Research Council (MC_UU_00028/2)