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A riboside hydrolase that salvages both nucleobases and nicotinamide in the auxotrophic parasite Trichomonas vaginalis.

ABSTRACT: Pathogenic parasites of the Trichomonas genus are causative agents of sexually transmitted diseases affecting millions of individuals worldwide and whose outcome may include stillbirths and enhanced cancer risks and susceptibility to HIV infection. Trichomonas vaginalis relies on imported purine and pyrimidine nucleosides and nucleobases for survival, since it lacks the enzymatic activities necessary for de novo biosynthesis. Here we show that T. vaginalis additionally lacks homologues of the bacterial or mammalian enzymes required for the synthesis of the nicotinamide ring, a crucial component in the redox cofactors NAD⁺ and NADP. Moreover, we show that a yet fully uncharacterized T. vaginalis protein homologous to bacterial and protozoan nucleoside hydrolases is active as a pyrimidine nucleosidase but shows the highest specificity toward the NAD⁺ metabolite nicotinamide riboside. Crystal structures of the trichomonal riboside hydrolase in different states reveals novel intermediates along the nucleoside hydrolase-catalyzed hydrolytic reaction, including an unexpected asymmetry in the homotetrameric assembly. The active site structure explains the broad specificity toward different ribosides and offers precise insights for the engineering of specific inhibitors that may simultaneously target different essential pathways in the parasite.

SUBMITTER: Patrone M

PROVIDER: S-EPMC10474468 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature

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A riboside hydrolase that salvages both nucleobases and nicotinamide in the auxotrophic parasite Trichomonas vaginalis.

Patrone Marco M Galasyn Gregory S GS Kerin Fiona F Nyitray Mattias M MM Parkin David W DW Stockman Brian J BJ Degano Massimo M

The Journal of biological chemistry 20230721 9

Pathogenic parasites of the Trichomonas genus are causative agents of sexually transmitted diseases affecting millions of individuals worldwide and whose outcome may include stillbirths and enhanced cancer risks and susceptibility to HIV infection. Trichomonas vaginalis relies on imported purine and pyrimidine nucleosides and nucleobases for survival, since it lacks the enzymatic activities necessary for de novo biosynthesis. Here we show that T. vaginalis additionally lacks homologues of the ba ...[more]

PMID: 37482279

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Project description:Trichomonas vaginalis is a unicellular parasite and responsible for one of the most common sexually transmittable infections worldwide, trichomoniasis. Carbonic anhydrases (CAs) are enzymes found in all lifeforms and are known to play a vital role in many biochemical processes in organisms including the maintenance of acid-base homeostasis. To date, eight evolutionarily divergent but functionally convergent forms of CAs (α, β, γ, δ, ζ, η, θ, and ι) have been discovered. The human genome contains only α-CAs, whereas many clinically significant pathogens express only β-CAs and/or γ-CAs. The characterization of pathogenic β- and γ-CAs provides important knowledge for targeting these biomolecules to develop novel anti-invectives against trichomoniasis. Here, we report the recombinant production and characterization of the second β-CA of T. vaginalis (TvaCA2). Light scattering analysis revealed that TvaCA2 is a dimeric protein, which was further supported with in silico modeling, suggesting similar structures between TvaCA2 and the first β-CA of T. vaginalis (TvaCA1). TvaCA2 exhibited moderate catalytic activity with the following kinetic parameters: kcat of 3.8 × 105 s-1 and kcat/KM of 4.4 × 107 M-1 s-1. Enzyme activity inhibition was studied with a set of clinically used sulfonamides and sulfonamide derivates. Twenty-seven out of the 39 compounds resulted in inhibition with a nanomolar range. These initial results encourage for future work entailing the design of more potent inhibitors against TvaCA2, which may provide new assets to fight trichomoniasis. KEY MESSAGES: • Protozoan parasite Trichomonas vaginalis has two β-carbonic anhydrases (TvaCA1/2). • TvaCA1/TvaCA2 represents promising targets for antitrichomonal drug development. • TvaCA2 is a dimer of 20.3 kDa and possesses moderate catalytic activity. • The most efficient inhibitor was clinical drug acetazolamide with KI of 222.9 nM. • The 39 tested sulfonamides form the basis for the design of more potent inhibitors.

Dataset Information

A riboside hydrolase that salvages both nucleobases and nicotinamide in the auxotrophic parasite Trichomonas vaginalis.

Publications

A riboside hydrolase that salvages both nucleobases and nicotinamide in the auxotrophic parasite Trichomonas vaginalis.

Similar Datasets

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