Abstract:
Previous studies have identified trypanolysin as a bloodmeal induced protein from the
midgut of tsetse fly (Glossina spp.), with a non-denaturing (NATIVE) molecular weight of -669
kDa and two subunit molecular weights of 55 kDa and 29 kDa under denaturing conditions.
Trypanolysin was shown to lyse only bloodstream-form but not procyclic-form trypanosomes,
Leishmania major and the cellular stage of Plasmodium Jalciparum. The mechanism of
trypanolysin-mediated lysis of trypanosomes was elucidated in this study by assessing its
binding properties on bloodstream-form T. b. brucei. The lytic activity of trypanolysin was
inhibited by specific chemical modifiers; N-acetylimidazole and Diethylpyrocarbonate
suggesting that histidine and tyrosine residues may be essential for its biological activity.
Furthermore, purified trypanolysin was resolved on a non-denaturing PAGE, transfered
onto nitrocellulose paper and its ability to bind to biotinylated T. b. brucei Variant surface
glycoprotein (VSG) assessed by staining with streptavidin horseradish peroxidase. Binding of
trypanolysin to VSG was ascertained further using gel retardation assays on NATIVE
Polyacrylamide Gel Electrophoresis (PAGE). The ability of trypanolysin to bind to VSG in both
cases suggests that the VSG is the recognition site for trypanolysin and this may be the vital
initial step in the lysis of bloodstream-form trypanosomes.
