ABSTRACT
Trypanosoma brucei is an important human pathogen. In this study, we have focused on the characterization of FtsH protease, ATP-dependent membrane-bound mitochondrial enzyme important for regulation of protein abundance. We have determined localization and orientation of all six putative T.brucei FtsH homologs in the inner mitochondrial membrane by in silico analyses, by immunofluorescence, and with protease assay. The evolutionary origin of these homologs has been tested by comparative phylogenetic analysis. Surprisingly, some kinetoplastid FtsH proteins display inverted orientation in the mitochondrial membrane compared to related proteins of other examined eukaryotes. Moreover, our data strongly suggest that during evolution the orientation of FtsH protease in T. brucei varied due to both loss and acquisition of the transmembrane domain.
Subject(s)
Evolution, Molecular , Mitochondrial Proteins/chemistry , Peptide Hydrolases/chemistry , Protozoan Proteins/chemistry , Trypanosoma brucei brucei/enzymology , Animals , Arabidopsis/classification , Arabidopsis/enzymology , Arabidopsis/genetics , Conserved Sequence , Euglena gracilis/classification , Euglena gracilis/enzymology , Euglena gracilis/genetics , Euglena longa/classification , Euglena longa/enzymology , Euglena longa/genetics , Gene Expression , Humans , Isoenzymes/chemistry , Isoenzymes/genetics , Isoenzymes/metabolism , Leishmania major/classification , Leishmania major/enzymology , Leishmania major/genetics , Mice , Mitochondria/enzymology , Mitochondria/genetics , Mitochondrial Membranes/chemistry , Mitochondrial Membranes/enzymology , Mitochondrial Proteins/genetics , Mitochondrial Proteins/metabolism , Peptide Hydrolases/genetics , Peptide Hydrolases/metabolism , Phylogeny , Protein Domains , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Saccharomyces cerevisiae/classification , Saccharomyces cerevisiae/enzymology , Saccharomyces cerevisiae/genetics , Trypanosoma brucei brucei/classification , Trypanosoma brucei brucei/geneticsABSTRACT
Trypanosomatids are unicellular parasites living in a wide range of host environments, which to large extent shaped their mitochondrial energy metabolism, resulting in quite large differences even among closely related flagellates. In a comparative manner, we analyzed the activities and composition of mitochondrial respiratory complexes in four species (Leishmania tarentolae, Crithidia fasciculata, Phytomonas serpens and Trypanosoma brucei), which represent the main model trypanosomatids. Moreover, we measured the activity of mitochondrial glycerol-3-phosphate dehydrogenase, the overall oxygen consumption and the mitochondrial membrane potential in each species. The comparative analysis suggests an inverse relationship between the activities of respiratory complexes I and II, as well as the overall activity of the canonical complexes and glycerol-3-phosphate dehydrogenase. Our comparative analysis shows that mitochondrial functions are highly variable in these versatile parasites.
Subject(s)
Oxidative Phosphorylation , Trypanosomatina/metabolism , Electron Transport , Glycerolphosphate Dehydrogenase/metabolism , Membrane Potential, Mitochondrial , Mitochondria/enzymology , Mitochondria/metabolism , Oxygen/metabolism , Trypanosomatina/geneticsABSTRACT
Euglena gracilis is a fresh-water flagellate possessing secondary chloroplasts of green algal origin. In contrast with organisms possessing primary plastids, mRNA levels of nucleus-encoded genes for chloroplast proteins in E. gracilis depend on neither light nor plastid function. However, it remains unknown, if all these mRNAs are trans-spliced and possess spliced leader sequence at the 5'-end and if trans-splicing depends on light or functional plastids. This study revealed that polyadenylated mRNAs encoding the chloroplast proteins glyceraldehyde-3-phosphate dehydrogenase (GapA), cytochrome f (PetA), and subunit O of photosystem II (PsbO) are trans-spliced irrespective of light or plastid function.
