title: LACK, a RACK1 ortholog, facilitates cytochrome c oxidase subunit expression to promote Leishmania major fitness.
abstract: Leishmania are kinetoplastid parasites that cause the sandfly-transmitted disease leishmaniasis. To maintain fitness throughout their infectious life cycle, Leishmania must undergo rapid metabolic adaptations to the dramatically distinct environments encountered during transition between sandfly and vertebrate hosts. We performed proteomic and immunoblot analyses of attenuated L. major strains deficient for LACK, the Leishmania ortholog of the mammalian receptor for activated c kinase (RACK1), that is important for parasite thermotolerance and virulence. This approach identified cytochrome c oxidase (LmCOX) subunit IV as a LACK-dependent fitness protein. Consistent with decreased levels of LmCOX subunit IV at mammalian temperature, and in amastigotes, LmCOX activity and mitochondrial function were also impaired in LACK-deficient L. major under these conditions. Importantly, overexpression of LmCOX subunit IV in LACK-deficient L. major restored thermotolerance and macrophage infectivity. Interestingly, overexpression of LmCOX subunit IV enhanced LmCOX subunit VI expression at mammalian temperature. Collectively, our data suggest LACK promotes Leishmania adaptation to the mammalian host environment by sustaining LmCOX subunit IV expression and hence energy metabolism in response to stress stimuli such as heat. These findings extend the repertoire of RACK1 protein utility to include a role in mitochondrial function.
authors.affiliation: Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, USA.
authors.forename: Daviel
authors.initials: D
authors.lastname: Cardenas
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Carter
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Nation
authors.forename: Juan C
authors.initials: JC
authors.lastname: Pizarro
authors.forename: Jessie
authors.initials: J
authors.lastname: Guidry
authors.forename: Ashok
authors.initials: A
authors.lastname: Aiyar
authors.forename: Ben L
authors.initials: BL
authors.lastname: Kelly
mesh_terms: D003576:Electron Transport Complex IV / Q000235:genetics* / Q000502:physiology*; D056084:Genetic Fitness; D006358:Hot Temperature; D015151:Immunoblotting; D018320:Leishmania major / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D008018:Life Cycle Stages; D008264:Macrophages / Q000469:parasitology; D008928:Mitochondria / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D040901:Proteomics; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism*; D000075370:Receptors for Activated C Kinase
chemical_list: D010455:Peptides; D015800:Protozoan Proteins; D000075370:Receptors for Activated C Kinase; C070301:peptide I; D003576:Electron Transport Complex IV