title: Effect of protease inhibitors on exflagellation in Plasmodium falciparum.
abstract: Enzymes involved in sexual differentiation and fertilization of the human malaria parasite Plasmodium falciparum represent potential targets for transmission blocking strategies. Parasite proteases are putatively involved in several steps during fertilization, but the types of proteases, their targets and modes of action remain hitherto unknown. We investigated the involvement of proteases in gametogenesis via exflagellation and immunofluorescence assays, using a variety of commercially available as well as newly designed protease inhibitors. The assays revealed a blockade of microgamete formation by the cysteine/serine protease inhibitors TLCK and TPCK. The serine protease inhibitor PMSF, the falcipain-targeting inhibitor RV112D, and the aspartic protease inhibitor EPNP also significantly decreased formation of microgametes. The metalloprotease inhibitor 1,10-phenanthroline, on the other hand, inhibited exflagellation by interfering with microgamete motility. Furthermore, EPNP reduced the activation of male and female gametocytes. Our data point to a major involvement of serine proteases and a non-thermolysin-like zinc metalloprotease in microgametocyte exflagellation.
authors.affiliation: Research Center for Infectious Diseases, University of Würzburg, Röntgenring 11, 97070 Würzburg, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Rupp
authors.forename: Rebecca
authors.initials: R
authors.lastname: Bosse
authors.forename: Tanja
authors.initials: T
authors.lastname: Schirmeister
authors.forename: Gabriele
authors.initials: G
authors.lastname: Pradel
mesh_terms: D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000037:antagonists & inhibitors; D015853:Cysteine Proteinase Inhibitors; D005407:Flagella / Q000378:metabolism*; D045726:Metalloproteases / Q000037:antagonists & inhibitors; D021261:Parasitic Sensitivity Tests; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology*; D011480:Protease Inhibitors / Q000145:classification* / Q000494:pharmacology*; D012098:Reproduction / Q000187:drug effects / Q000502:physiology; D012697:Serine Endopeptidases / Q000187:drug effects*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D014107:Tosyllysine Chloromethyl Ketone / Q000494:pharmacology; D014108:Tosylphenylalanyl Chloromethyl Ketone / Q000494:pharmacology
chemical_list: D015853:Cysteine Proteinase Inhibitors; D011480:Protease Inhibitors; D015842:Serine Proteinase Inhibitors; D014107:Tosyllysine Chloromethyl Ketone; D014108:Tosylphenylalanyl Chloromethyl Ketone; D045726:Metalloproteases; D012697:Serine Endopeptidases; D016282:Aspartic Acid Endopeptidases