title: Plasmodium falciparum phospholipase C hydrolyzing sphingomyelin and lysocholinephospholipids is a possible target for malaria chemotherapy.
abstract: Sphingomyelinase (SMase) is one of the principal enzymes in sphingomyelin (SM) metabolism. Here, we identified a Plasmodium falciparum gene (PfNSM) encoding a 46-kD protein, the amino acid sequence of which is approximately 25% identical to that of bacteria SMases. Biochemical analyses of the recombinant protein GST-PfNSM, a fusion protein of the PfNSM product with glutathione-S-transferase, reveal that this enzyme retained similar characteristics in various aspects to SMase detected in P. falciparum-infected erythrocytes and isolated parasites. In addition, the recombinant protein retains hydrolyzing activity not only of SM but also of lysocholinephospholipids (LCPL) including lysophosphatidylcholine and lysoplatelet-activating factor, indicating that PfNSM encodes SM/LCPL-phospholipase C (PLC). Scyphostatin inhibited SM/LCPL-PLC activities of the PfNSM product as well as the intraerythrocytic proliferation of P. falciparum in a dose-dependent manner with ID(50) values for SM/LCPL-PLC activities and the parasite growth at 3-5 microM and approximately 7 microM, respectively. Morphological analysis demonstrated most severe impairment in the intraerythrocytic development with the addition of scyphostatin at trophozoite stage than at ring or schizont stages, suggesting its effect specifically on the stage progression from trophozoite to schizont, coinciding with the active transcription of PfNSM gene.
authors.affiliation: Department of Biochemistry and Cell Biology, Japan Science and Technology Corporation, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo 162-8640, Japan. hanak@nih.go.jp
authors.forename: Kentaro
authors.initials: K
authors.lastname: Hanada
authors.forename: Nirianne Marie Q
authors.initials: NM
authors.lastname: Palacpac
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Magistrado
authors.forename: Ken
authors.initials: K
authors.lastname: Kurokawa
authors.forename: Ganesh
authors.initials: G
authors.lastname: Rai
authors.forename: Daiji
authors.initials: D
authors.lastname: Sakata
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hara
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Horii
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nishijima
authors.forename: Toshihide
authors.initials: T
authors.lastname: Mitamura
mesh_terms: D000577:Amides / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D017125:Genes, Protozoan; D008244:Lysophosphatidylcholines / Q000378:metabolism; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D010972:Platelet Activating Factor / Q000031:analogs & derivatives* / Q000378:metabolism; D011753:Pyrones / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism; D013379:Substrate Specificity; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000577:Amides; D008244:Lysophosphatidylcholines; C029271:O-deacetyl platelet activating factor; D010972:Platelet Activating Factor; D011753:Pyrones; D011994:Recombinant Proteins; D013109:Sphingomyelins; C121123:scyphostatin; D010738:Type C Phospholipases; D013108:Sphingomyelin Phosphodiesterase