Proteases from Trypanosoma brucei brucei

Abstract

African trypanosomes contain proteases that may be released into the bloodstream of their infected hosts. This paper describes a novel, combined isolation of a cysteine proteinase (called trypanopain-Tb) and a serine oligopeptidase (which we call oligopeptidase-Tb) from Trypanosoma brucei brucei, as well as a comparison of the activities of these two enzymes against several host regulatory molecules.The enzymes differed in various respects. Firstly, purified trypanopain-Tb was shown to readily cleave proteins such as gelatin maximally at acidic pH. In contrast, oligopeptidase-Tb, which is optimally active at alkaline pH, did not hydrolyse proteins larger than 4 kDa. However, it readily hydrolysed various polypeptides, including neurotensin and atrial natriuretic factor.The interaction of the two enzymes with mammalian protease inhibitors also differed. Cystatins and a,-macroglobulin effectively inhibited trypanopain-Tb, with the K, values for cystatin C and low-molecular-mass kininogen (-1O-~" M) predicting that trypanopain-Tb is likely to be effectively controlled by these inhibitors if released into the host bloodstream. In contrast, oligopeptidase-Tb was not inhibited by serpins or a,-macroglobulin, suggesting that it may remain active if released into the host bloodstream. In support of these in v i t m results, the blood of trypanosome-infected rats displayed no trypanopain-Tblike activity, but exhibited high oligopeptidase-Tb-like activity. Thus, while trypanopain-Tb seems likely to be confined to an intracellular role within the parasite, oligopeptidase-Tb has the potential to remain active in the host bloodstream and so contribute directly to pathogenesis.

A trypanosome oligopeptidase as a target for the trypanocidal agents pentamidine, diminazene and suramin

“…However, OP-Tb activity is enhanced in the presence of reducing agents and polyamines [8]. Since melarsoprol therapy depletes intracellular reducing agents (namely trypanothione) and since DFMO therapy depletes intracellular polyamine levels [28] either drug may down-regulate OP-Tb activity within trypanosomes through the depletion of intracellular OP-Tb activators.…”

Biological Roles of Peptidases in Trypanosomatids~!2009-11-26~!2010-02-15~!2010-03-18~!

“…congolense possesses at least two families of CPs, named CP1 and CP2, the latter also known as congopain or trypanopain-Tc [207], while the enzymes in T. b. brucei and T. b. rhodesiense are termed trypanopain-Tb (or brucipain) and rhodesain, respectively [204,205].…”

“…These enzymes share structural and functional similarities with T. cruzi cruzipain [203][204][205][206].…”

“…Detection of procongopain and trypanosomal enzymatic activity in the plasma of T. congolense-infected cattle suggests that the enzyme may interact with host proteins during infection, such as to reduce the proliferation of bovine peripheral blood mononuclear cells in response to mitogens and antigens, as well as to interact with bovine kininogens to trigger the release of kinins [206]. It is also known that -2-macroglobulin effectively inhibits cysteine peptidase activity in African trypanosomes [204]. These data, together with the capacity of procongopain to be activated at a weakly basic pH, suggest that procongopain may be extracellularly processed in the presence of blood vessel glycosaminoglycans, supporting the hypothesis that the enzyme acts as a pathogenic factor in the interaction of the parasite with its host [211].…”

Trypanosome-Derived Oligopeptidase B Is Released into the Plasma of Infected Rodents, Where It Persists and Retains Full Catalytic Activity

“…It has previously been shown that OP-Tb isolated directly from trypanosomes was not inhibited by mammalian plasma serpins (17). OP-Tb activity is therefore unregulated after release into the bloodstream.…”