8w7h
From Proteopedia
Purine Nucleoside Phosphorylase in complex with MMV000848
Structural highlights
FunctionPNPH_PLAF7 As part of the purine salvage pathway, catalyzes the phosphorolytic breakdown of the N-glycosidic bond in the beta-(deoxy)ribonucleoside molecules, with the formation of the corresponding free purine bases and pentose-1-phosphate (PubMed:18957439, PubMed:14982926, PubMed:16131758, PubMed:19575810, PubMed:24416224, PubMed:29440412). Preferentially acts on inosine and guanosine, and to a lesser extent on 2'-deoxyguanosine and guanosine (PubMed:14982926, PubMed:16131758, PubMed:19575810). Also catalyzes the phosphorylation of S-methyl-5'-thioinosine (MTI) to hypoxanthine; MTI is produced by adenosine deaminase (ADA)-mediated breakdown of S-methyl-5'-thioadenosine (MTA), a major by-product of polyamine biosynthesis (PubMed:18957439, PubMed:14982926, PubMed:24416224). Generates hypoxanthine from both the purine salvage pathway and from polyamine metabolism which is required for nucleic acids synthesis (PubMed:18957439, PubMed:14982926, PubMed:24416224). Has no activity towards adenosine (By similarity).[UniProtKB:Q8T9Z7][1] [2] [3] [4] [5] [6] Publication Abstract from PubMedAbout 247 million cases of malaria occurred in 2021 with Plasmodium falciparum accounting for the majority of 619,000 deaths. In the absence of a widely available vaccine, chemotherapy remains crucial to prevent, treat, and contain the disease. The efficacy of several drugs currently used in the clinic is likely to suffer from the emergence of resistant parasites. A global effort to identify lead compounds led to several initiatives such as the Medicine for Malaria Ventures (MMV), a repository of compounds showing promising efficacy in killing the parasite in cell-based assays. Here, we used mass spectrometry coupled with cellular thermal shift assay to identify putative protein targets of MMV000848, a compound with an in vitro EC50 of 0.5 muM against the parasite. Thermal shift assays showed a strong increase of P. falciparum purine nucleoside phosphorylase (PfPNP) melting temperature by up to 15 degrees C upon incubation with MMV000848. Binding and enzymatic assays returned a K(D) of 1.52 +/- 0.495 muM and an IC(50) value of 21.5 +/- 2.36 muM. The inhibition is competitive with respect to the substrate, as confirmed by a cocrystal structure of PfPNP bound with MMV000848 at the active site, determined at 1.85 A resolution. In contrast to transition states inhibitors, MMV000848 specifically inhibits the parasite enzyme but not the human ortholog. An isobologram analysis shows subadditivity with immucillin H and with quinine respectively, suggesting overlapping modes of action between these compounds. These results point to PfPNP as a promising antimalarial target and suggest avenues to improve inhibitor potency. Identification and structural validation of purine nucleoside phosphorylase from Plasmodium falciparum as a target of MMV000848.,Chung Z, Lin J, Wirjanata G, Dziekan JM, El Sahili A, Preiser PR, Bozdech Z, Lescar J J Biol Chem. 2023 Dec 21;300(1):105586. doi: 10.1016/j.jbc.2023.105586. PMID:38141766[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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