The Plasma Membrane of Bloodstream-form African Trypanosomes Confers Susceptibility and Specificity to Killing by Hydrophobic Peptides |
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Authors: | John M. Harrington Justin Widener Natalie Stephens Thomas Johnson Maria Francia Paul Capewell Annette Macleod Stephen L. Hajduk |
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Affiliation: | From the ‡Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602 and ;the §Wellcome Trust Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, Faculty of Veterinary Medicine, University of Glasgow, Glasgow G12 8TA, Scotland, United Kingdom |
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Abstract: | Trypanosoma brucei is the causative agent of both a veterinary wasting disease and human African trypanosomiasis, or sleeping sickness. The cell membrane of the developmental stage found within the mammalian host, the bloodstream form (BSF), is highly dynamic, exhibiting rapid rates of endocytosis and lateral flow of glycosylphosphatidylinositol-anchored proteins. Here, we show that the cell membrane of these organisms is a target for killing by small hydrophobic peptides that increase the rigidity of lipid bilayers. Specifically, we have derived trypanocidal peptides that are based upon the hydrophobic N-terminal signal sequences of human apolipoproteins. These peptides selectively partitioned into the plasma membrane of BSF trypanosomes, resulting in an increase in the rigidity of the bilayer, dramatic changes in cell motility, and subsequent cell death. No killing of the developmental stage found within the insect midgut, the procyclic form, was observed. Additionally, the peptides exhibited no toxicity toward mammalian cell lines and did not induce hemolysis. Studies with model liposomes indicated that bilayer fluidity dictates the susceptibility of membranes to manipulation by hydrophobic peptides. We suggest that the composition of the BSF trypanosome cell membrane confers a high degree of fluidity and unique susceptibility to killing by hydrophobic peptides and is therefore a target for the development of trypanocidal drugs. |
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Keywords: | Cell Death Liposomes Membrane Membrane Biophysics Parasitology Anisotropy Membrane Fluidity Peptides Pharmaceutical Agent Trypanosome |
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