Insights into the role of gp63-like proteins in lower trypanosomatids

Abstract

Any actual understanding of trypanosomatids in general requires a comprehensive analysis of the less-specialized species as thorough as our knowledge of the more specialized Leishmania and Trypanosoma. In this context, we have shown by antibody cross-reactivity that purified extracellular metallopeptidases from Phytomonas françai, Crithidia deanei (cured strain) and Crithidia guilhermei share common epitopes with the leishmanial gp63. Flow cytometry and fluorescence microscopy analyses indicated the presence of gp63-like molecules on the cell surface of these lower trypanosomatids. Binding assays with explanted guts of Aedes aegypti incubated with purified gp63 and the pretreatment of trypanosomatids with anti-gp63 antibodies indicated that the gp63-like molecules are involved in the adhesive process of these trypanosomatids to the A. aegypti gut wall. In addition, our results indicate for the first time that the gp63-like molecule binds to a polypeptide of 50 kDa on the A. aegypti gut epithelium extract.

Major Surface Protease of Trypanosomatids: One Size Fits All?

“…Metalloprotease activity has been detected using fibrinogen as a substrate, suggesting that the genes are functional in these protozoa (35). Immunoreactive MSPlike proteins have been detected in Leptomonas seymouri, Crithidia luciliae (51), C. deanei (29), Crithidia guilhermei (64), and Blastocrithidia culicis (26) using antibodies to leishmanial MSPs in immunoblots. In addition, two 50-and 58-kDA metalloproteases of B. culicis possess a GPI anchor (26).…”

“…In addition, two 50-and 58-kDA metalloproteases of B. culicis possess a GPI anchor (26). Even more interesting, 67-and 62-kDa proteins in the total cellular lysates of C. deanei and C. guilhermei share common epitopes with leishmanial MSP and are localized on the cell surface (64). These MSP-like proteins function in the binding of the protozoa to the extracted gut of A. aegypti, possibly through a ligand of 50 kDa (64).…”

“…This metalloprotease, along with another 62-kDa protein, shares common epitopes with the leishmanial MSP and is localized on the cell surface. They play a role in protozoan binding to the extracted gut of Aedes aegypti, possibly through a 50-kDa ligand (64). Phytomonas serpens, the parasite of tomato fruits, has metalloprotease activity at molecular masses between 70 and 94 kDa exclusively in the extracellular stage (100).…”

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

“…2). At least to Aedes aegypti, a suitable experimental model to study the interaction of monoxenous trypanosomatids and insects, a receptor of 50 kDa for the gp63 purified molecule was identified in the protein insect gut extract [28].…”

“…Typically, the cellular gp63-like molecules were mainly attached to the cell surface by a GPI anchor; however, a small amount of this enzyme can be detected in cytoplasmic compartments, which may indicate the occurrence of hydrophilic isoforms, or the detection of enzymatic activity from precursor molecules that are further transported to the plasma membrane [13]. Curiously, two distinct populations with different affinities for the anti-gp63 antibody were identified in H. samuelpessoai, L. wallacei, C. deanei and C. guilhermei by means of flow cytometry analyses, indicating that gp63-related molecules are not equally expressed on the surface of trypanosomatid cells [19,28,231]. The lack of equal expression may be correlated to the parasites growth and/or cell cycle phases, since flagellate cultures were not synchronized.…”