A systematic approach to understand the mechanism of action of the bisthiazolium compound T4 on the human malaria parasite, Plasmodium falciparum.
BACKGROUND
In recent years, a major increase in the occurrence of drug resistant falciparum malaria has been reported. Choline analogs, such as the bisthiazolium T4, represent a novel class of compounds with strong potency against drug sensitive and resistant P. falciparum clones. Although T4 and its analogs are presumed to target the parasite's lipid metabolism, their exact mechanism of action remains unknown. Here we have employed transcriptome and proteome profiling analyses to characterize the global response of P. falciparum to T4 during the intraerythrocytic cycle of this parasite.


RESULTS
No significant transcriptional changes were detected immediately after addition of T4 despite the drug's effect on the parasite metabolism. Using the Ontology-based Pattern Identification (OPI) algorithm with an increased T4 incubation time, we demonstrated cell cycle arrest and a general induction of genes involved in gametocytogenesis. Proteomic analysis revealed a significant decrease in the level of the choline/ethanolamine-phosphotransferase (PfCEPT), a key enzyme involved in the final step of synthesis of phosphatidylcholine (PC). This effect was further supported by metabolic studies, which showed a major alteration in the synthesis of PC from choline and ethanolamine by the compound.


CONCLUSIONS
Our studies demonstrate that the bisthiazolium compound T4 inhibits the pathways of synthesis of phosphatidylcholine from choline and ethanolamine in P. falciparum, and provide evidence for post-transcriptional regulations of parasite metabolism in response to external stimuli.
Le Roch
Karine G
KG
Department of Cell Biology and Neuroscience, University of California, Riverside, 900 University Avenue, Riverside, CA 92521, USA. karine.leroch@ucr.edu
Johnson
Jeffrey R
JR
Ahiboh
Hugues
H
Chung
Duk-Won D
DW
Prudhomme
Jacques
J
Plouffe
David
D
Henson
Kerstin
K
Zhou
Yingyao
Y
Witola
William
W
Yates
John R
JR
Mamoun
Choukri Ben
CB
Winzeler
Elizabeth A
EA
Vial
Henri
H
D000465:Algorithms; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured; D002794:Choline / Q000378:metabolism; D004912:Erythrocytes / Q000469:parasitology; D004983:Ethanolamines / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D010713:Phosphatidylcholines / Q000096:biosynthesis; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics*; D020543:Proteome / Q000235:genetics; D016053:RNA, Protozoan / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053719:Tandem Mass Spectrometry; D013844:Thiazoles / Q000494:pharmacology*; D014158:Transcription, Genetic; D017855:Transferases (Other Substituted Phosphate Groups) / Q000378:metabolism
C499115:1,12-bis(4-methyl-5-(2-methoxyethyl)thiazol-3-ium-3-yl)dodecane; D000962:Antimalarials; D004983:Ethanolamines; D010713:Phosphatidylcholines; D020543:Proteome; D016053:RNA, Protozoan; D013844:Thiazoles; D017855:Transferases (Other Substituted Phosphate Groups); C119514:choline-ethanolaminephosphotransferase; D002794:Choline