| - | Malaria remains a major threat to human health, as strains resistant to current therapeutics are discovered. Efforts in finding new drug targets are hampered by the lack of sufficiently specific tools to provide target validation prior to initiating expensive drug discovery projects. Thus, new approaches that can rapidly enable drug target validation are of significant interest. In this manuscript we present the crystal structure of malate dehydrogenase from Plasmodium falciparum (PfMDH) at 2.4 A resolution and structure-based mutagenic experiments interfering with the inter-oligomeric interactions of the enzyme. We report decreased thermal stability, significantly decreased specific activity and kinetic parameters of PfMDH mutants upon mutagenic disruption of either oligomeric interface. In contrast, stabilization of one of the interfaces resulted in increased thermal stability, increased substrate/cofactor affinity and hyperactivity of the enzyme towards malate production at sub-millimolar substrate concentrations. Furthermore, the presented data show that our designed PfMDH mutant could be used as specific inhibitor of the wild type PfMDH activity, as mutated PfMDH copies were shown to be able to self-incorporate into the native assembly upon introduction in vitro, yielding deactivated mutant:wild-type species. These data provide an insight into the role of oligomeric assembly in regulation of PfMDH activity and reveal that recombinant mutants could be used as probe tool for specific modification of the wild type PfMDH activity, thus offering the potential to validate its druggability in vivo without recourse to complex genetics or initial tool compounds. Such tool compounds often lack specificity between host or pathogen proteins (or are toxic in in vivo trials) and result in difficulties in assessing cause and effect-particularly in cases when the enzymes of interest possess close homologs within the human host. Furthermore, our oligomeric interference approach could be used in the future in order to assess druggability of other challenging human pathogen drug targets.
| + | Malate dehydrogenases (MDHs) sustain tumor growth and carbon metabolism by pathogens including Plasmodium falciparum. However, clinical success of MDH inhibitors is absent, as current small molecule approaches targeting the active site are unselective. The presence of an allosteric binding site at oligomeric interface allows the development of more specific inhibitors. To this end we performed a differential NMR-based screening of 1500 fragments to identify fragments that bind at the oligomeric interface. Subsequent biophysical and biochemical experiments of an identified fragment indicate an allosteric mechanism of 4-(3,4-difluorophenyl) thiazol-2-amine (4DT) inhibition by impacting the formation of the active site loop, located >30 A from the 4DT binding site. Further characterization of the more tractable homolog 4-phenylthiazol-2-amine (4PA) and 16 other derivatives are also reported. These data pave the way for downstream development of more selective molecules by utilizing the oligomeric interfaces showing higher species sequence divergence than the MDH active site. |
| - | Oligomeric interfaces as a tool in drug discovery: Specific interference with activity of malate dehydrogenase of Plasmodium falciparum in vitro.,Lunev S, Butzloff S, Romero AR, Linzke M, Batista FA, Meissner KA, Muller IB, Adawy A, Wrenger C, Groves MR PLoS One. 2018 Apr 25;13(4):e0195011. doi: 10.1371/journal.pone.0195011., eCollection 2018. PMID:29694407<ref>PMID:29694407</ref>
| + | A fragment-based approach identifies an allosteric pocket that impacts malate dehydrogenase activity.,Reyes Romero A, Lunev S, Popowicz GM, Calderone V, Gentili M, Sattler M, Plewka J, Taube M, Kozak M, Holak TA, Domling ASS, Groves MR Commun Biol. 2021 Aug 10;4(1):949. doi: 10.1038/s42003-021-02442-1. PMID:34376783<ref>PMID:34376783</ref> |
| | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> |
