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Start Over Author "Kinkead, James" Topic glycolysis
3 results on '"Kinkead, James"'

1. Fast acting allosteric phosphofructokinase inhibitors block trypanosome glycolysis and cure acute African trypanosomiasis in mice.

Author

McNae IW, Kinkead J, Malik D, Yen LH, Walker MK, Swain C, Webster SP, Gray N, Fernandes PM, Myburgh E, Blackburn EA, Ritchie R, Austin C, Wear MA, Highton AJ, Keats AJ, Vong A, Dornan J, Mottram JC, Michels PAM, Pettit S, and Walkinshaw MD

Subjects
Acute Disease, Allosteric Regulation drug effects, Animals, Hep G2 Cells, Humans, Inhibitory Concentration 50, Kaplan-Meier Estimate, Mice, Parasites drug effects, Phosphofructokinases chemistry, Phosphofructokinases metabolism, Protein Binding drug effects, Protein Kinase Inhibitors chemistry, Protein Kinase Inhibitors pharmacokinetics, Protein Kinase Inhibitors therapeutic use, Protein Multimerization, Structure-Activity Relationship, Trypanosoma drug effects, Trypanosomiasis, African drug therapy, Glycolysis drug effects, Phosphofructokinases antagonists & inhibitors, Protein Kinase Inhibitors pharmacology, Trypanosoma enzymology, Trypanosomiasis, African metabolism, Trypanosomiasis, African parasitology
Abstract

The parasitic protist Trypanosoma brucei is the causative agent of Human African Trypanosomiasis, also known as sleeping sickness. The parasite enters the blood via the bite of the tsetse fly where it is wholly reliant on glycolysis for the production of ATP. Glycolytic enzymes have been regarded as challenging drug targets because of their highly conserved active sites and phosphorylated substrates. We describe the development of novel small molecule allosteric inhibitors of trypanosome phosphofructokinase (PFK) that block the glycolytic pathway resulting in very fast parasite kill times with no inhibition of human PFKs. The compounds cross the blood brain barrier and single day oral dosing cures parasitaemia in a stage 1 animal model of human African trypanosomiasis. This study demonstrates that it is possible to target glycolysis and additionally shows how differences in allosteric mechanisms may allow the development of species-specific inhibitors to tackle a range of proliferative or infectious diseases.

Published
2021
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2. Kinetic and structural studies of Trypanosoma and Leishmania phosphofructokinases show evolutionary divergence and identify AMP as a switch regulating glycolysis versus gluconeogenesis.

Author

Fernandes PM, Kinkead J, McNae IW, Vásquez-Valdivieso M, Wear MA, Michels PAM, and Walkinshaw MD

Subjects
Adenosine Monophosphate chemistry, Amino Acid Sequence, Animals, Biological Evolution, Catalytic Domain, Crystallography, X-Ray, Gluconeogenesis, Guanosine Triphosphate chemistry, Humans, Kinetics, Models, Molecular, Protein Conformation, Species Specificity, Substrate Specificity, Adenosine Monophosphate metabolism, Glycolysis, Guanosine Triphosphate metabolism, Leishmania enzymology, Phosphofructokinases chemistry, Phosphofructokinases metabolism, Trypanosoma brucei brucei enzymology
Abstract

Trypanosomatids possess glycosome organelles that contain much of the glycolytic machinery, including phosphofructokinase (PFK). We present kinetic and structural data for PFK from three human pathogenic trypanosomatids, illustrating intriguing differences that may reflect evolutionary adaptations to differing ecological niches. The activity of Leishmania PFK - to a much larger extent than Trypanosoma PFK - is reliant on AMP for activity regulation, with 1 mm AMP increasing the L. infantum PFK (LiPFK) kcat/K 0.5 value by 10-fold, compared to only a 1.3- and 1.4-fold increase for T. cruzi and T. brucei PFK, respectively. We also show that Leishmania PFK melts at a significantly lower (> 15 °C) temperature than Trypanosoma PFKs and that addition of either AMP or ATP results in a marked stabilization of the protein. Sequence comparisons of Trypanosoma spp. and Leishmania spp. show that divergence of the two genera involved amino acid substitutions that occur in the enzyme's 'reaching arms' and 'embracing arms' that determine tetramer stability. The dramatic effects of AMP on Leishmania activity compared with the Trypanosoma PFKs may be explained by differences between the T-to-R equilibria for the two families, with the low-melting Leishmania PFK favouring the flexible inactive T-state in the absence of AMP. Sequence comparisons along with the enzymatic and structural data presented here also suggest there was a loss of AMP-dependent regulation in Trypanosoma species rather than gain of this characteristic in Leishmania species and that AMP acts as a key regulator in Leishmania governing the balance between glycolysis and gluconeogenesis.F6P value by 10-fold, compared to only a 1.3- and 1.4-fold increase for T. cruzi and T. brucei PFK, respectively. We also show that Leishmania PFK melts at a significantly lower (> 15 °C) temperature than Trypanosoma PFKs and that addition of either AMP or ATP results in a marked stabilization of the protein. Sequence comparisons of Trypanosoma spp. and Leishmania spp. show that divergence of the two genera involved amino acid substitutions that occur in the enzyme's 'reaching arms' and 'embracing arms' that determine tetramer stability. The dramatic effects of AMP on Leishmania activity compared with the Trypanosoma PFKs may be explained by differences between the T-to-R equilibria for the two families, with the low-melting Leishmania PFK favouring the flexible inactive T-state in the absence of AMP. Sequence comparisons along with the enzymatic and structural data presented here also suggest there was a loss of AMP-dependent regulation in Trypanosoma species rather than gain of this characteristic in Leishmania species and that AMP acts as a key regulator in Leishmania governing the balance between glycolysis and gluconeogenesis., (© 2019 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Published
2020
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3. Study of the molecular regulation of trypanosomatid phosphofructokinases as drug targets

Author

Kinkead, James Robert H., Walkinshaw, Malcolm, and Wear, Martin

Subjects
572, Trypanosoma brucei, Trypanosoma cruzi, Leishmania infantum, African Sleeping Sickness, Chagas disease, Leishmaniasis, glycolysis, phosphofructokinase, PFK
Abstract

The trypanosomatid parasites T. brucei, T. cruzi and Leishmania spp. are responsible for the ‘neglected diseases’ Human African Trypanosomiasis, Chagas disease and Leishmaniasis respectively. In their human infective form in the bloodstream all three trypanosomatid parasites rely heavily on glycolysis for ATP production. Phosphofructokinase (PFK) catalyses the third step of the glycolytic pathway in all organisms using aerobic respiration. It facilitates the phospho transfer from ATP to fructose 6-phosphate (F6P) to make the products fructose 1,6- bisphosphate (F16BP) and ADP. RNAi knockout of T. brucei PFK has shown the enzyme is essential for survival of the bloodstream form parasites. Trypanosomatid PFKs have a unique set of structural and regulatory differences compared to the mammalian host enzyme. These differences, coupled with the availability of trypanosomatid PFK crystal structures present an opportunity for the structure-based design of specific inhibitors against the enzyme. Here we present an enzymatic characterisation of recombinant PFKs from T. brucei, T. cruzi and Leishmania infantum trypanosomatids, their regulation by the allosteric activator AMP, and their inhibition by drug-like inhibitor compounds. Inhibitor compounds (‘CTCB compounds’) were designed against T. brucei PFK with the aim of developing novel treatments against Human African Trypanosomiasis (HAT). We describe the testing, ranking and biophysical characterisation of these compounds as part of a Wellcome Trust Seeding Drug Discovery program. We found that CTCB inhibitor compounds bound to an allosteric pocket unique to trypanosomatid PFKs. We show that the compounds are specific; neither competing with the natural substrates ATP or F6P nor inhibiting the human PFK enzyme. We describe the development and testing of highly potent and specific low molecular weight PFK inhibitors that translate to both killing of cultured T. b. brucei parasites and a cure of stage I HAT in mice models. We describe the tight, 1:1 binding of these compounds with trypanosomatid PFKs, and the thermodynamic characteristics of binding through various biophysical assays. We also show the unprecedented characterisation of the reverse PFK reaction by trypanosomatid and human forms of the enzymes. We found that PFK can also carry out the reverse enzymatic reaction, under physiologically relevant concentrations of ADP and F16BP to produce F6P and ATP. We show that the reverse reaction is also subject to allosteric regulation by AMP, and can be inhibited by the CTCB compounds with a similar potency to the forward reaction. Finally, we describe the mechanism of allosteric activation by AMP and inhibition by the drug-like compounds against trypanosomatid PFKs.

Published
2018

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