Kinetic and Molecular Docking Studies to Determine the Effect of Inhibitors on the Activity and Structure of Fused G6PD::6PGL Protein from Trichomonas vaginalis.

Víctor Martínez-Rosas,Rodrigo Aguayo-Ortiz,Saúl Gómez-Manzo,Isabel Baeza-Ramírez,Fernando Gómez-Chávez,Abigail González-Valdez,Roberto Arreguin-Espinosa,Gabriel Navarrete-Vázquez,Beatriz Hernández-Ochoa,Sergio Enríquez-Flores,Laura Morales-Luna,Verónica Pérez De La Cruz,Carlos Wong-Baeza,Carlos Martínez-Conde

doi:10.3390/molecules27041174

Abstract

Trichomoniasis is a sexually transmitted disease with a high incidence worldwide, affecting 270 million people. Despite the existence of a catalog of available drugs to combat this infection, their extensive use promotes the appearance of resistant Trichomonas vaginalis (T. vaginalis), and some side effects in treated people, which are reasons why it is necessary to find new alternatives to combat this infection. In this study, we investigated the impact of an in-house library comprising 55 compounds on the activity of the fused T. vaginalis G6PD::6PGL (TvG6PD::6PGL) protein, a protein mediating the first reaction step of the pentose phosphate pathway (PPP), a crucial pathway involved in the parasite’s energy production. We found four compounds: JMM-3, CNZ-3, CNZ-17, and MCC-7, which inhibited the TvG6PD::6PGL protein by more than 50%. Furthermore, we determined the IC50, the inactivation constants, and the type of inhibition. Our results showed that these inhibitors induced catalytic function loss of the TvG6PD::6PGL enzyme by altering its secondary and tertiary structures. Finally, molecular docking was performed for the best inhibitors, JMM-3 and MCC-7. All our findings demonstrate the potential role of these selected hit compounds as TvG6PD::6PGL enzyme selective inhibitors.

Highlights

Trichomoniasis is a sexually transmitted disease (STD) caused by the protozoan Trichomonas vaginalis (T. vaginalis)
We found that Josue Martínez-Miranda (JMM)-3 showed uncompetitive-type inhibition for both physiological substrates, G6P and NADP+ (Figure 4A,B), implying that one or more substrates bind to the enzyme before the inhibitor
While MCC-7 formed two H-bonds between Asn372 and the nitrogen of acetamide group of MCC-7, and the second H-bond was formed with Arg356 and thiazolidine ring (Figure 7E), the most stable conformer showed ∆G = −7.38 kcal/mol (Figure 8E). These results revealed that JMM-3 and MCC-7 probably do not affect the binding of substrates because they are not competitive inhibitors, but they probably affect the correct positioning of the NADP+

Summary

Introduction

Trichomoniasis is a sexually transmitted disease (STD) caused by the protozoan Trichomonas vaginalis (T. vaginalis). This disease is considered a global health problem, with around 270 million people affected per year, and has an estimated prevalence of 8.1% for women and 1.0% for men [1,2,3,4]. Hydrogenosomes are organelles involved in energy metabolism, where the pyruvate is oxidized to produce ATP [10,11]. Another important pathway in the metabolism of T. vaginalis is the pentose phosphate pathway (PPP), which is involved in the generation of reduced nicotinamide-adenine-dinucleotide phosphate (NADPH). The PPP provides nucleotide precursors, such as ribose 5-phosphate, to synthesize nucleic acids and metabolic intermediates, such as fructose-6-phosphate and glyceraldehyde-3-phosphate [12]

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