Identification and initial characterisation of Trypanosoma Cox17 copper metallochaperone

Abstract

Copper plays an essential role in organisms as a catalytic co-factor for key enzymes like cytochrome c oxidase. Copper importation, distribution and secretion is carried out by copper transport and copper-binding proteins known as copper chaperones. Cox17 is a chaperone that conveys copper to Cox11 and Sco1 for metalation of the Cu_B and Cu_A of Cox1 and Cox2 respectively in eukaryotes. Cox17 from Trypanosoma brucei brucei and T. congolense were recombinantly expressed and affinity purified as MBP-fusion proteins. An ascorbic acid oxidation assay, a BCA-release assay and an in vivo growth inhibition assay confirmed the presence of copper bound to the proteins. Trypanosomal Cox17 and other copper-binding proteins are expressed at higher levels in the insect procyclic stage where cytochrome c oxidase is active, compared to the bovine bloodstream forms. In silico docking models suggests possible interaction partners for Cox17.