A study of PBLP in the rodent malaria parasite Plasmodium yoelii showed that it has an important role in invasion. Deletion of PBLP affects merozoite formation, sporozoite maturation, and infectivity
(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Eukaryota: NE > Alveolata: NE > Apicomplexa: NE > Aconoidasida: NE > Haemosporida: NE > Plasmodiidae: NE > Plasmodium: NE > Plasmodium (Laverania): NE > Plasmodium falciparum: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MRIIKYIFFAFIILALFVCALNTYIYLKQDSFVFSNEFPTVEEKNQTLGE NYEIVTLTTKDNHKFTCWYIKTKDSENKPIMLYFQGNGGYLEKYMNLFNL IIERVDVNIFSCSNRGCGSNIAKPSEEYFYKDAHVYIEYVKTKNPKHLFI FGSSMGAAVAIDTALKQHDHISGLIVQNAFTSLKELSRYSHPFLNYFLFD YDMIIRSKMDNETKIKNITVPTLFTLSEMDEKVPTSHTRTLFQLSASTNK QLYLSKGGTHPNILKNDDGSYHKAMKKFIVTAISIREKNIQKAVERNPNT PN
Salinipostin A (Sal A) is a potent antiplasmodial marine natural product with an undefined mechanism of action. Using a Sal A-derived activity-based probe, we identify its targets in the Plasmodium falciparum parasite. All of the identified proteins contain alpha/beta serine hydrolase domains and several are essential for parasite growth. One of the essential targets displays a high degree of homology to human monoacylglycerol lipase (MAGL) and is able to process lipid esters including a MAGL acylglyceride substrate. This Sal A target is inhibited by the anti-obesity drug Orlistat, which disrupts lipid metabolism. Resistance selections yielded parasites that showed only minor reductions in sensitivity and that acquired mutations in a PRELI domain-containing protein linked to drug resistance in Toxoplasma gondii. This inability to evolve efficient resistance mechanisms combined with the non-essentiality of human homologs makes the serine hydrolases identified here promising antimalarial targets.
Title: Functional annotation of serine hydrolases in the asexual erythrocytic stage of Plasmodium falciparum Elahi R, Ray WK, Dapper C, Dalal S, Helm RF, Klemba M Ref: Sci Rep, 9:17532, 2019 : PubMed
Enzymes of the serine hydrolase superfamily are ubiquitous, highly versatile catalysts that mediate a wide variety of metabolic reactions in eukaryotic cells, while also being amenable to selective inhibition. We have employed a fluorophosphonate-based affinity capture probe and mass spectrometry to explore the expression profile and metabolic roles of the 56-member P. falciparum serine hydrolase superfamily in the asexual erythrocytic stage of P. falciparum. This approach provided a detailed census of active serine hydrolases in the asexual parasite, with identification of 21 active serine hydrolases from alpha/beta hydrolase, patatin, and rhomboid protease families. To gain insight into their functional roles and substrates, the pan-lipase inhibitor isopropyl dodecylfluorophosphonate was employed for competitive activity-based protein profiling, leading to the identification of seven serine hydrolases with potential lipolytic activity. We demonstrated how a chemoproteomic approach can provide clues to the specificity of serine hydrolases by using a panel of neutral lipase inhibitors to identify an enzyme that reacts potently with a covalent monoacylglycerol lipase inhibitor. In combination with existing phenotypic data, our studies define a set of serine hydrolases that likely mediate critical metabolic reactions in asexual parasites and enable rational prioritization of future functional characterization and inhibitor development efforts.
The bud emergence (BEM)46 proteins are evolutionarily conserved members of the alpha/beta-hydrolase superfamily, which includes enzymes with diverse functions and a wide range of substrates. Here, we identified a Plasmodium BEM46-like protein (PBLP) and characterized it throughout the life cycle of the rodent malaria parasite Plasmodium yoelii. The Plasmodium BEM46-like protein is shown to be closely associated with the parasite plasma membrane of asexual erythrocytic stage schizonts and exo-erythrocytic schizonts; however, PBLP localizes to unique intracellular structures in sporozoites. Generation and analysis of P. yoelii knockout (Deltapblp) parasite lines showed that PBLP has an important role in erythrocytic stage merozoite development with Deltapblp parasites forming fewer merozoites during schizogony, which results in decreased parasitemia when compared with wild-type (WT) parasites. Deltapblp parasites showed no defects in gametogenesis or transmission to mosquitoes; however, because they formed fewer oocysts there was a reduction in the number of developed sporozoites in infected mosquitoes when compared with WT. Although Deltapblp sporozoites showed no apparent defect in mosquito salivary gland infection, they showed decreased infectivity in hepatocytes in vitro. Similarly, mice infected with Deltapblp sporozoites exhibited a delay in the onset of blood-stage patency, which is likely caused by reduced sporozoite infectivity and a discernible delay in exo-erythrocytic merozoite formation. These data are consistent with the model that PBLP has an important role in parasite invasive-stage morphogenesis throughout the parasite life cycle.
