Identification and initial characterisation of Trypanosoma Cox17 copper metallochaperone.

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 CuB and CuA 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.