title: Characterization of a Leishmania stage-specific mitochondrial membrane protein that enhances the activity of cytochrome c oxidase and its role in virulence.
abstract: Leishmaniasis is caused by the dimorphic protozoan parasite Leishmania. Differentiation of the insect form, promastigotes, to the vertebrate form, amastigotes, and survival inside the vertebrate host accompanies a drastic metabolic shift. We describe a gene first identified in amastigotes that is essential for survival inside the host. Gene expression analysis identified a 27 kDa protein-encoding gene (Ldp27) that was more abundantly expressed in amastigotes and metacyclic promastigotes than in procyclic promastigotes. Immunofluorescence and biochemical analysis revealed that Ldp27 is a mitochondrial membrane protein. Co-immunoprecipitation using antibodies to the cytochrome c oxidase (COX) complex, present in the inner mitochondrial membrane, placed the p27 protein in the COX complex. Ldp27 gene-deleted parasites (Ldp27(-/-)) showed significantly less COX activity and ATP synthesis than wild type in intracellular amastigotes. Moreover, the Ldp27(-/-) parasites were less virulent both in human macrophages and in BALB/c mice. These results demonstrate that Ldp27 is an important component of an active COX complex enhancing oxidative phosphorylation specifically in infectious metacyclics and amastigotes and promoting parasite survival in the host. Thus, Ldp27 can be explored as a potential drug target and parasites devoid of the p27 gene could be considered as a live attenuated vaccine candidate against visceral leishmaniasis.
authors.affiliation: Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, FDA, Bethesda, MD, USA.
authors.forename: Ranadhir
authors.initials: R
authors.lastname: Dey
authors.forename: Claudio
authors.initials: C
authors.lastname: Meneses
authors.forename: Poonam
authors.initials: P
authors.lastname: Salotra
authors.forename: Shaden
authors.initials: S
authors.lastname: Kamhawi
authors.forename: Hira L
authors.initials: HL
authors.lastname: Nakhasi
authors.forename: Robert
authors.initials: R
authors.lastname: Duncan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003576:Electron Transport Complex IV / Q000378:metabolism*; D005260:Female; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006801:Humans; D007891:Leishmania / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D008264:Macrophages / Q000469:parasitology*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D024101:Mitochondrial Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010085:Oxidative Phosphorylation; D015800:Protozoan Proteins / Q000378:metabolism*; D016053:RNA, Protozoan / Q000235:genetics; D016415:Sequence Alignment; D014774:Virulence
chemical_list: D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D015800:Protozoan Proteins; D016053:RNA, Protozoan; D003576:Electron Transport Complex IV