Cleavage of trypanosome surface glycoproteins by alkaline trypsin-like enzyme(s) in the midgut of Glossina morsitans

摘要: EP and GPEET procyclin, the major surface glycoproteins of procyclic forms Trypanosoma brucei, are truncated by proteases in midgut tsetse fly Glossina morsitans morsitans. We show that soluble extracts from midguts teneral flies contain trypsin-like enzymes cleave N-terminal domains living culture-derived parasites. The same extract shows little activity against a variant glycoprotein on bloodstream form T. brucei (MITat 1.2) none glutamic acid/alanine-rich protein, congolense insect although both these proteins potential trypsin cleavage sites. Gel filtration revealed three peaks tryptic procyclins. Trypsin alone would be sufficient to account for at single arginine residue fly. In contrast, processing multiple sites require additional might only induced or activated during feeding infection. Unexpectedly, pH optima procyclin reaction digestion trypsin-specific synthetic substrate Chromozym-TRY were extremely alkaline (pH 10). Direct measurements made within different compartments digestive tract. conclude gut flies, proventriculus hindgut, is alkaline, contradiction previous indicating it was mildly acidic. When analysed 48 h after their first bloodmeal, gradient 10.6+/-0.6) posterior 7.9+/-0.4) observed.