title: Divergence of Erv1-associated mitochondrial import and export pathways in trypanosomes and anaerobic protists.
abstract: In yeast (Saccharomyces cerevisiae) and animals, the sulfhydryl oxidase Erv1 functions with Mia40 in the import and oxidative folding of numerous cysteine-rich proteins in the mitochondrial intermembrane space (IMS). Erv1 is also required for Fe-S cluster assembly in the cytosol, which uses at least one mitochondrially derived precursor. Here, we characterize an essential Erv1 orthologue from the protist Trypanosoma brucei (TbERV1), which naturally lacks a Mia40 homolog. We report kinetic parameters for physiologically relevant oxidants cytochrome c and O(2), unexpectedly find O(2) and cytochrome c are reduced simultaneously, and demonstrate that efficient reduction of O(2) by TbERV1 is not dependent upon a simple O(2) channel defined by conserved histidine and tyrosine residues. Massive mitochondrial swelling following TbERV1 RNA interference (RNAi) provides evidence that trypanosome Erv1 functions in IMS protein import despite the natural absence of the key player in the yeast and animal import pathways, Mia40. This suggests significant evolutionary divergence from a recently established paradigm in mitochondrial cell biology. Phylogenomic profiling of genes also points to a conserved role for TbERV1 in cytosolic Fe-S cluster assembly. Conversely, loss of genes implicated in precursor delivery for cytosolic Fe-S assembly in Entamoeba, Trichomonas, and Giardia suggests fundamental differences in intracellular trafficking pathways for activated iron or sulfur species in anaerobic versus aerobic eukaryotes.
authors.affiliation: Biology Centre, Institute of Parasitology, Czech Academy of Sciences and Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic.
authors.forename: Somsuvro
authors.initials: S
authors.lastname: Basu
authors.forename: Joanne C
authors.initials: JC
authors.lastname: Leonard
authors.forename: Nishal
authors.initials: N
authors.lastname: Desai
authors.forename: Despoina A I
authors.initials: DA
authors.lastname: Mavridou
authors.forename: Kong Ho
authors.initials: KH
authors.lastname: Tang
authors.forename: Alan D
authors.initials: AD
authors.lastname: Goddard
authors.forename: Michael L
authors.initials: ML
authors.lastname: Ginger
authors.forename: Julius
authors.initials: J
authors.lastname: Lukeš
authors.forename: James W A
authors.initials: JW
authors.lastname: Allen
mesh_terms: D019943:Amino Acid Substitution; D045304:Cytochromes c / Q000737:chemistry; D019143:Evolution, Molecular; D055785:Gene Knockdown Techniques; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology / Q000648:ultrastructure; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000235:genetics; D008933:Mitochondrial Swelling; D016297:Mutagenesis, Site-Directed; D016877:Oxidants; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics; D010100:Oxygen / Q000737:chemistry; D010802:Phylogeny; D017510:Protein Folding; D021381:Protein Transport; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics; D034622:RNA Interference; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000201:enzymology*; D050862:Oxidoreductases Acting on Sulfur Group Donors
chemical_list: D045304:Cytochromes c; D024101:Mitochondrial Proteins; D016877:Oxidants; D010088:Oxidoreductases; D010100:Oxygen; D015800:Protozoan Proteins; D050862:Oxidoreductases Acting on Sulfur Group Donors