(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 MFHLYELLMFFLRHPRDEYNEEFLGPIFMHFYDKNYYRKDLIIKNRRGEK LKCSFFTPFNYNENTPCVIYTHSASSCQLEVLDILHILLLCECSIFSYDC SGCGLSDGYYSTKGWNESQDLYLLLNHLHYVEKIKNFVLWGKYSGAVSSI IAAALYGNIKLLILDSPYVSLIELYKTTFHLNAKKKGEIFFKNVCLYLVR KQIKKKFHYDINNVCPIFFIEDITIPTIYIISKNDKIVHPVHSLYFAYKQ QKAYKIFYISESSTQTYENFSYENKLTLA
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.
