Inhibitors of Trypanosoma brucei 6-Phosphogluconate Dehydrogenase

Hanau, Stefania; Montin, Katy; Gilbert, Ian H.; Barrett, Michael P.; Dallocchio, Franco

doi:10.2174/157340707781695587

Cited by 6 publications

(4 citation statements)

References 36 publications

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“…Drugs designed to combat African trypanosomiasis are often based on the pentose phosphate pathway enzyme, 6‐phosphogluconate dehydrogenase (decarboxylating, 6PGDH, EC 1.1.1.44) [1,2]. This tropical infectious disease is caused by protozoan parasites of the Trypanosoma brucei species, of the order Kinetoplastida, to which Leishmania and the American Trypanosoma cruzi also belong.…”

Section: Binding Parameters Of Substrate and Substrate Analogues To mentioning

confidence: 99%

Thermodynamic characterization of substrate and inhibitor binding to Trypanosoma brucei 6‐phosphogluconate dehydrogenase

et al. 2007

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6‐Phosphogluconate dehydrogenase is a potential target for new drugs against African trypanosomiasis. Phosphorylated aldonic acids are strong inhibitors of 6‐phosphogluconate dehydrogenase, and 4‐phospho‐d‐erythronate (4PE) and 4‐phospho‐d‐erythronohydroxamate are two of the strongest inhibitors of the Trypanosoma brucei enzyme. Binding of the substrate 6‐phospho‐d‐gluconate (6PG), the inhibitors 5‐phospho‐d‐ribonate (5PR) and 4PE, and the coenzymes NADP, NADPH and NADP analogue 3‐amino‐pyridine adenine dinucleotide phosphate to 6‐phospho‐d‐gluconate dehydrogenase from T. brucei was studied using isothermal titration calorimetry. Binding of the substrate (Kd = 5 µm) and its analogues (Kd =1.3 µm and Kd = 2.8 µm for 5PR and 4PE, respectively) is entropy driven, whereas binding of the coenzymes is enthalpy driven. Oxidized coenzyme and its analogue, but not reduced coenzyme, display a half‐site reactivity in the ternary complex with the substrate or inhibitors. Binding of 6PG and 5PR poorly affects the dissociation constant of the coenzymes, whereas binding of 4PE decreases the dissociation constant of the coenzymes by two orders of magnitude. In a similar manner, the Kd value of 4PE decreases by two orders of magnitude in the presence of the coenzymes. The results suggest that 5PR acts as a substrate analogue, whereas 4PE mimics the transition state of dehydrogenation. The stronger affinity of 4PE is interpreted on the basis of the mechanism of the enzyme, suggesting that the inhibitor forces the catalytic lysine 185 into the protonated state.

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Section: Binding Parameters Of Substrate and Substrate Analogues To mentioning

confidence: 99%

Thermodynamic characterization of substrate and inhibitor binding to Trypanosoma brucei 6‐phosphogluconate dehydrogenase

et al. 2007

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“…Thus, since we did not find an increase in 6 PG as previously reported in cancer cells, it seems that the inhibition of 6 PG dehydrogenase (6 PGD) by 6ANADP is not the main 6AN effect in Leishmania. In agreement, significant differences were found between the human and the kinetoplastid enzyme [76][77][78][79][80]. Furthermore, since the 6ANAD/P were not found, it can be deduced that the glycohydrolases that catalyse transglycosidation and produce 6ANAD/P from 6AN are not so active in Leishmania, as well as in other microorganisms [28][29][30][31] and they probably possess β-NAD + glycohydrolases of a different type.…”

Section: Discussionmentioning

confidence: 71%

Influence of 6-aminonicotinamide (6AN) on Leishmania promastigotes evaluated by metabolomics: Beyond the pentose phosphate pathway

Almugadam

Trentini

Maritati

et al. 2018

Chemico-Biological Interactions

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6-Aminonicotinamide (6AN) is an antimetabolite used to inhibit the NADPH-producing pentose phosphate pathway (PPP) in many cellular systems, making them more susceptible to oxidative stress. It is converted by a NAD(P) glycohydrolase to 6-aminoNAD and 6-aminoNADP, causing the accumulation of PPP intermediates, due to their inability to participate in redox reactions. Some parasites like Plasmodium falciparum and Coccidia are highly sensitive but not all cell types showed a strong responsiveness to 6AN, probably due to the different targeted pathway. For instance, in bacteria the main target is the Preiss-Handler salvage pathway for NAD biosynthesis. We were interested in testing 6AN on the kinetoplastid protozoan Leishmania as another model to clarify the mechanisms of action of 6AN, by using metabolomics. Leishmania promastigotes, the life-cycle stage residing in the sandfly, demonstrated a three order of magnitude higher EC50 (mM) compared to P. falciparum and mammalian cells (μM), although pre-treatment with 100 μM 6AN prior to sub-lethal oxidative challenge induced a supra-additive cell kill in L. infantum. By metabolomics, we did not detect 6ANAD/P suggesting that NAD glycohydrolases in Leishmania may not be highly efficient in catalysing transglycosidation as happens in other microorganisms. Contrariwise to the reported effect on 6AN-treated cancer cells, we did not detect 6-phosphogluconate (6 PG) accumulation, indicating that 6ANADP cannot bind with high affinity to the PPP enzyme 6 PG dehydrogenase. By contrast, 6AN caused a profound phosphoribosylpyrophosphate (PRPP) decrease and nucleobases accumulation confirming that PPP is somehow affected. More importantly, we found a decrease in nicotinate production, evidencing the interference with the Preiss-Handler salvage pathway for NAD biosynthesis, most probably by inhibiting the reaction catalysed by nicotinamidase. Therefore, our combined data from Leishmania strains, though confirming the interference with PPP, also showed that 6AN impairs the Preiss-Handler pathway, underlining the importance to develop compounds targeting this last route.

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“…Given its importance in metabolism, 6PGDH has been studied as a drug target in cancer (Hitosugi et al, 2012;Lin et al, 2015;Yang et al, 2018) and in a number of infectious diseases (Barrett & Gilbert, 2002;Hanau et al, 2004Hanau et al, , 2007Esteve & Cazzulo, 2004;Gonza ´lez et al, 2011;Kerkhoven et al, 2013;Haeussler et al, 2018;Wang et al, 2021;Jakkula et al, 2021), attempting to exploit differences between the host enzyme and the homologous microbial enzyme (Hanau et al, 1996;Bertelli et al, 2001;Dardonville et al, 2003Dardonville et al, , 2004Montin et al, 2007;Ruda et al, 2010;Morales-Luna et al, 2021). Also, 6PGDH is a target for enzyme and metabolic engineering, with the aim of improving the productivity of biocatalysts for useful compounds, such as l-lysine and riboflavin (Ohnishi et al, 2005;Wang et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

6-Phosphogluconate dehydrogenase and its crystal structures

Hanau

Helliwell

2022

Acta Cryst Sect F

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6-Phosphogluconate dehydrogenase (6PGDH; EC 1.1.1.44) catalyses the oxidative decarboxylation of 6-phosphogluconate to ribulose 5-phosphate in the context of the oxidative part of the pentose phosphate pathway. Depending on the species, it can be a homodimer or a homotetramer. Oligomerization plays a functional role not only because the active site is at the interface between subunits but also due to the interlocking tail-modulating activity, similar to that of isocitrate dehydrogenase and malic enzyme, which catalyse a similar type of reaction. Since the pioneering crystal structure of sheep liver 6PGDH, which allowed motifs common to the β-hydroxyacid dehydrogenase superfamily to be recognized, several other 6PGDH crystal structures have been solved, including those of ternary complexes. These showed that more than one conformation exists, as had been suggested for many years from enzyme studies in solution. It is inferred that an asymmetrical conformation with a rearrangement of one of the two subunits underlies the homotropic cooperativity. There has been particular interest in the presence or absence of sulfate during crystallization. This might be related to the fact that this ion, which is a competitive inhibitor that binds in the active site, can induce the same 6PGDH configuration as in the complexes with physiological ligands. Mutagenesis, inhibitors, kinetic and binding studies, post-translational modifications and research on the enzyme in cancer cells have been complementary to the crystallographic studies. Computational modelling and new structural studies will probably help to refine the understanding of the functioning of this enzyme, which represents a promising therapeutic target in immunity, cancer and infective diseases. 6PGDH also has applied-science potential as a biosensor or a biobattery. To this end, the enzyme has been efficiently immobilized on specific polymers and nanoparticles. This review spans the 6PGDH literature and all of the 6PGDH crystal structure data files held by the Protein Data Bank.

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Inhibitors of Trypanosoma brucei 6-Phosphogluconate Dehydrogenase

Cited by 6 publications

References 36 publications

Thermodynamic characterization of substrate and inhibitor binding to Trypanosoma brucei 6‐phosphogluconate dehydrogenase

Thermodynamic characterization of substrate and inhibitor binding to Trypanosoma brucei 6‐phosphogluconate dehydrogenase

Influence of 6-aminonicotinamide (6AN) on Leishmania promastigotes evaluated by metabolomics: Beyond the pentose phosphate pathway

6-Phosphogluconate dehydrogenase and its crystal structures

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