Oligopeptidase B from Trypanosoma brucei, a New Member of an Emerging Subgroup of Serine Oligopeptidases

Abstract

Trypanosoma brucei contains a soluble serine oligopeptidase (OP-Tb) that is released into the host bloodstream during infection, where it has been postulated to participate in the pathogenesis of African trypanosomiasis. Here, we report the identification of a single copy gene encoding the T. brucei oligopeptidase and a homologue from the related trypanosomatid pathogen Leishmania major. The enzymes encoded by these genes belong to an emerging subgroup of the prolyl oligopeptidase family of serine hydrolases, referred to as oligopeptidase B. The trypanosomatid oligopeptidases share 70% amino acid sequence identity with oligopeptidase B from the intracellular pathogen Trypanosoma cruzi, which has a demonstrated role in mammalian host cell signaling and invasion. OP-Tb exhibited no activity toward the prolyl oligopeptidase substrate H-Gly-Pro-7-amido-4-methylcoumarin. Instead, it had activity toward substrates of trypsin-like enzymes, particularly those that have basic amino acids in both P 1 and P 2 (e.g. benzyloxycarbonyl-Arg-Arg-7-amido-4-methylcoumarin k cat /K m ‫؍‬ 529 s ؊1 M ؊1). The activity of OP-Tb was enhanced by reducing agents and by polyamines, suggesting that these agents may act as in vivo regulators of OP-Tb activity. This study provides the basis of the characterization of a novel subgroup of serine oligopeptidases from kinetoplastid protozoa with potential roles in pathogenesis.

Oligopeptidase B-2 from Leishmania amazonensis with an unusual C-terminal extension

“…Two oligopetidases B have been identified in the L. major genome. The first one was demonstrated by Morty (1999) and then annotated by the genome project (Ivens et al 2005), confirming the presence of this enzyme previously characterized in other trypanosomatids. The other oligopeptidase B was denominated oligopeptidase B-like.…”

“…A pair of residues, Asp 460 and Asp 462, was defined for bacterial oligopeptidase B that may be involved in defining P2 specificity (Morty et al 2002, Gerczei et al 2000. Trypanosome oligopeptidases B demonstrate great similarity, since they have two glutamic acids at the same position (Morty et al 1999). However, in oligopeptidases B-2 from trypanosomatids, serine and histidine were observed at the same position.…”

The Oligopeptidase B of Leishmania Regulates Parasite Enolase and Immune Evasion

“…Oligopeptidase B (OPB) 2 has been identified in other protozoa, including T. cruzi, Trypanosoma brucei, and Trypanosoma evansi (7)(8)(9). These enzymes represent a subfamily of potential chemotherapeutic targets (10) because their inhibitors have been shown to be trypanocidal (4,11,12).…”

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

“…African trypanosomes also contain a serine oligopeptidase, oligopeptidase B (OpdB), which is implicated in the pathogenesis of these parasites, since it is released into the bloodstream of infected mammalian hosts [219][220][221], where it retains its catalytic activity and may participate in the anomalous degradation of host peptide hormones [222]. In this sense, oligopeptidases B display similar properties to several hormone-processing enzymes, thus host-peptide hormones are candidates for cleavage by the parasite oligopeptidases [222].…”