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Abstract: The mitochondrial carrier family (MCF) is a group of structurally conserved proteins that mediate the transport of a wide range of metabolic intermediates across the mitochondrial inner membrane. In this paper, an overview of the mitochondrial carrier proteins (MCPs) of the early-branching kinetoplastid parasite Trypanosoma brucei brucei is presented. Sequence analysis and phylogenetic reconstruction gave insight into the evolution and conservation of the 24 identified TbMCPs; for most of these, putative transport functions could be predicted. Comparison of the kinetoplastid MCP inventory to those previously reported for other eukaryotes revealed remarkable deviations: T. b. brucei lacks genes encoding some prototypical MCF members, such as the citrate carrier and uncoupling proteins. The in vivo expression of the identified TbMCPs in the two replicating life-cycle forms of T. b. brucei, the bloodstream-form and procyclic-form, was quantitatively assessed at the mRNA level by Northern blot analysis. Immunolocalisation studies confirmed that majority of the 24 identified TbMCPs is found in the mitochondrion of procyclic-form T. b. brucei. [Copyright &y& Elsevier]

Abstract: Single nucleotide polymorphism (SNP) markers have been shown to be useful in genetic investigations of medically important parasites and their hosts. In this paper, we describe the prediction and validation of SNPs in ESTs of Schistosoma mansoni. We used 107,417 public sequences of S. mansoni and identified 15,614 high-quality candidate SNPs in 12,184 contigs. The presence of predicted SNPs was observed in well characterized antigens and vaccine candidates such as those coding for myosin; Sm14 and Sm23; cathepsin B and triosephosphate isomerase (TPI). Additionally, SNPs were experimentally validated for the cathepsin B. A comparative model of the S. mansoni cathepsin B was built for predicting the possible consequences of amino acid substitutions on the protein structure. An analysis of the substitutions indicated that the amino acids were mostly located on the surface of the molecule, and we found no evidence for a significant conformational change of the enzyme. However, at least one of the substitutions could result in a structural modification of an epitope. [Copyright &y& Elsevier]

• Trypanosoma brucei possesses 2 putative phosphate carriers, Tb MCP11 and Tb MCP8. • Tb MCP11 partially complements the yeast phosphate carrier knockout phenotype. • The depletion of Tb MCP11 is lethal in procyclic form. • Depletion of Tb MCP11 blocks mitochondrial ATP synthesis and oxygen consumption. • Cells in which Tb MCP11 was depleted display a severe cytokinesis defect. Conserved amongst all eukaryotes is a family of mitochondrial carrier proteins (SLC25A) responsible for the import of various solutes across the inner mitochondrial membrane. We previously reported that the human parasite Trypanosoma brucei possesses 26 SLC25A proteins (Tb MCPs) amongst which two, Tb MCP11 and Tb MCP8, were predicted to function as phosphate importers. The transport of inorganic phosphate into the mitochondrion is a prerequisite to drive ATP synthesis by substrate level and oxidative phosphorylation and thus crucial for cell viability. In this paper we describe the functional characterization of Tb MCP11. In procyclic form T. brucei , the RNAi of Tb MCP11 blocked ATP synthesis on mitochondrial substrates, caused a drop of the mitochondrial oxygen consumption and drastically reduced cell viability. The functional complementation in yeast and mitochondrial swelling experiments suggested a role for Tb MCP11 as inorganic phosphate carrier. Interestingly, procyclic form T. brucei cells in which Tb MCP11 was depleted displayed an inability to either replicate or divide the kinetoplast DNA, which resulted in a severe cytokinesis defect. [ABSTRACT FROM AUTHOR]