Trypanosoma brucei J protein 2 functionally cooperates with the cytosolic Hsp70.4 and Hsp70 proteins

The etiological agent of African trypanosomiasis, Trypanosoma brucei, has been identified to possess an expanded and diverse group of heat shock proteins, that have been implicated in cytoprotection, differentiation, and subsequently progression and transmission of the disease. Heat shock protein 70 is a highly conserved and ubiquitous molecular chaperone that is important in maintaining protein homeostasis in the cell. Its function is regulated by a wide range of co-chaperones; and inhibition of these functions and interactions with co-chaperones are emerging as potential therapeutic targets for numerous diseases. This study sought to biochemically characterize the cytosolic Hsp70 and Hsp70.4 proteins and to investigate if they form a functional partnership with the Type I J-protein, Tbj2. The cytosolic localisation of the proteins was confirmed by accessing the TrypTag endogenous tagging microscopy database. Expression of TbHsp70 was shown to be heat inducible, whilst TbHsp70.4 was constitutively expressed. The basal ATPase activities of TbHsp70.4 and TbHsp70 were stimulated by Tbj2. It was further determined that Tbj2 forms a functional partnership with TbHsp70 and TbHsp70.4 as the J-protein was shown to stimulate the ability of both proteins to mediate the refolding of chemically denatured {beta}-galactosidase. This study provides further insight into this important class of proteins which may contribute to the development of new therapeutic strategies to combat African Trypanosomiasis.