The detection of bovine lactoferrin binding protein on Trypanosoma brucei

Trypanosoma brucei, the causative agent of sleeping sickness in humans, requires transferrin (TF) for growth. Therefore, T. brucei has a TF receptor that allows it to obtain iron from TF. Lactoferrin (LF), a member of the TF family protein, is an iron-binding protein that is found in most biological fluids of mammals. LF has been shown to interact with some bacteria species by specific receptor-ligand binding. We examined the ability of T. brucei to bind bovine LF (bLF) by using a fluorescence test, streptavidin-biotin (SAB) microplate analysis, and far Western blotting using a biotin-streptavidin system. We found that bLF bound to components of T brucei, and that bLF hydrolysate disrupted the sites responsible for binding to parasite proteins. Furthermore, bLF, human LF, bovine TF, and ovotransferrin bound same proteins of T brucei, which exhibited molecular masses of 40 and 43 kDa. The N-terminal amino acid sequence of the 40 kDa bLF binding protein was identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH).