title: A proton pumping pyrophosphatase in the Golgi apparatus and plasma membrane vesicles of Trypanosoma cruzi.
abstract: The proton pumping pyrophosphatase (H(+)-PPase) is an enzyme that has been identified in membranes of plant vacuoles, in the Golgi complex of plants and Chlamydomonas reinhardtii, and more recently in acidocalcisomes of different trypanosomatids and apicomplexan parasites. Immunofluorescence and immunoelectron microscopy studies using antibodies against the plant enzyme also suggested a plasma membrane localization in different stages of Trypanosoma cruzi. In this report we provide immunogold electron microscopy evidence of the presence of the H(+)-PPase in the Golgi complex and plasma membrane of epimastigotes of T. cruzi. Pyrophosphate promoted acidification of plasma membrane vesicles as determined using acridine orange. This activity was stimulated by K(+) ions, inhibited by the pyrophosphate analogs imidodiphosphate (IDP) and aminomethylenediphosphonate (AMDP) by KF, NaF and DCCD, and it had different responses to ions and inhibitors as compared with the activity present in acidocalcisomes. Surface localization of the H(+)-PPase was confirmed by experiments using biotinylation of cell surface proteins and immunoprecipitation with antibodies against H(+)-PPase. Taken together, these results are consistent with the presence of a functional H(+)-PPase in the plasma membrane of these parasites.
authors.affiliation: Laboratory of Molecular Parasitology, Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, IL 61802, USA.
authors.forename: Rosa
authors.initials: R
authors.lastname: Martinez
authors.forename: Youhong
authors.initials: Y
authors.lastname: Wang
authors.forename: Gustavo
authors.initials: G
authors.lastname: Benaim
authors.forename: Marlene
authors.initials: M
authors.lastname: Benchimol
authors.forename: Wanderley
authors.initials: W
authors.lastname: de Souza
authors.forename: David A
authors.initials: DA
authors.lastname: Scott
authors.forename: Roberto
authors.initials: R
authors.lastname: Docampo
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006056:Golgi Apparatus / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D016253:Microscopy, Immunoelectron; D009994:Osmolar Concentration; D017494:Proton Pumps / Q000378:metabolism*; D011755:Pyrophosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014349:Trypanosoma cruzi / Q000166:cytology* / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D004791:Enzyme Inhibitors; D017494:Proton Pumps; D011755:Pyrophosphatases