Figure 2.

In silico reconstruction of metabolic pathways of Blastocystis sp. mitochondria-like organelles. The proteins are predicted from the combined analysis of MitoProt and MitoPred algorithms. Proteins with a predicted amino-terminal extension are outlined by a solid black line, and protein complexes for which mitochondrial presequences for only some of the subunits have been predicted are outlined by a dashed black line. The pathways in purple represent: (1) the conversion of pyruvate into acetyl-CoA by the pyruvate dehydrogenase complex (PDH), pyruvate:ferredoxin oxidoreductase (PFO) or pyruvate:NADP oxidoreductase (PNO); (2) acetyl-CoA is then converted to acetate by acetate:succinate CoA transferase (ASCT) and may allow production of ATP (3). Pyruvate may follow routes that potentially use complexes I and II to produce succinate (and propionate) and certainly participate in maintaining the redox balance. The pathways in green and burgundy correspond to amino acid metabolism and fatty acid metabolism, respectively. Pathways for the assembly of iron-sulfur proteins are represented in blue, and proteins involved in mitochondrial import machinery in orange. Enzymes that may play a role in protection against oxidative stress are indicated in pink (superoxide dismutase (SOD), alternative oxidase (AOX), glutathione reductase (GR) and gluthathione peroxidase (GPx)); the role of glycerol-3-phosphate dehydrogenase (G3PDH) remains to be determined. Abbreviations: 1, acetyl-CoA carboxylase; 2, 3-oxoacyl-ACP synthase; 3, 3-oxoacyl-ACP reductase; 4, 2-enoyl-ACP reductase; 5, methylmalonyl-CoA mutase; 6, methylmalonyl-CoA epimerase; 7, propionyl-CoA carboxylase; AAC, ATP/ADP translocator; ACP, acyl carrier protein; ALAT, alanine aminotransferase; BC-AAT, branched-chain amino acid aminotransferase; C I, complex I; ECH, enoyl-CoA hydratase; [Fe]-Hyd, [Fe]-hydrogenase; FRD/SDH, fumarate reductase/succinate dehydrogenase activity of complex II; FUM, fumarase; HCDH, 3-hydroxyacyl-CoA dehydrogenase; HICH, 3-hydroxyisobutyryl-CoA hydrolase; HID, 3-hydroxyisobutyrate dehydrogenase; LC-ACS, long-chain acyl-CoA synthetase; MDH, malate dehydrogenase; OMC, oxoglutarate/malate carrier protein; Pyr C, pyruvate carboxylase; SCS, succinyl-CoA synthetase; SOD, superoxide dismutase.