title: Mitochondrial localization of the threonine peptidase PfHslV, a ClpQ ortholog in Plasmodium falciparum.
abstract: Plasmodium falciparum belongs to a group of eukaryotes expressing an ortholog of the prokaryotic T1-threonine peptidase, heat shock locus V (HslV). Bacterial HslV is a particularly well studied protease, due to its structural and biochemical similarity to the eukaryotic proteasome. Plasmodium falciparum HslV (PfHslV) is expressed in schizonts and merozoites of the asexual blood stage. Strong sequence conservation between plasmodial species, absence of HslV homologs in the human genome, and availability of specific inhibitors led us to explore its function and potential use as a drug target. In a first step, we investigated localization of PfHslV, using a bioinformatics approach and a transgenic P. falciparum line expressing a PfHslV-enhanced yellow fluorescent protein (EYFP) fusion protein from the endogenous pfhslV locus. PfHslV-EYFP was found in the mitochondrial matrix under fluorescence and immunoelectron microscopy. Endogenous, non-modified PfHslV was present in purified mitochondria and interference with mitochondrial membrane potential by drug treatment led to impairment of PfHslV processing. Import of heterologous EYFP into the plasmodial mitochondrion is mediated by the N-terminal 37 amino acids of PfHslV. PfHslV's targeting sequence is also functional in human cells, demonstrating strong conservation of mitochondrial targeting in eukaryotes. In conclusion, our data shows that PfHslV is located to the plasmodial mitochondrion and presumably has vital function within this organelle which makes it an attractive target for interventions.
authors.affiliation: Eberhard Karls University, Institute of Tropical Medicine, Tübingen, Germany.
authors.forename: Serena
authors.initials: S
authors.lastname: Tschan
authors.forename: Andrea
authors.initials: A
authors.lastname: Kreidenweiss
authors.forename: York-Dieter
authors.initials: YD
authors.lastname: Stierhof
authors.forename: Nicole
authors.initials: N
authors.lastname: Sessler
authors.forename: Rolf
authors.initials: R
authors.lastname: Fendel
authors.forename: Benjamin
authors.initials: B
authors.lastname: Mordmüller
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019295:Computational Biology / Q000379:methods; D017930:Genes, Reporter; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D008928:Mitochondria / Q000201:enzymology*; D010447:Peptide Hydrolases / Q000302:isolation & purification* / Q000378:metabolism*; D010963:Plasmodium falciparum / Q000201:enzymology*; D021382:Protein Sorting Signals; D021381:Protein Transport; D015800:Protozoan Proteins / Q000302:isolation & purification / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D008164:Luminescent Proteins; D021382:Protein Sorting Signals; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; C054562:yellow fluorescent protein, Bacteria; D010447:Peptide Hydrolases