ArticleBMC infectious diseases2024
Metabolism of FAD, FMN and riboflavin (vitamin B2) in the human parasitic blood fluke Schistosoma mansoni.
Article in BMC infectious diseases, 2024. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
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1 citing paper in PubMed.
- Identification of Riboflavin Metabolism Pathway in HepG2 Cells Expressing Genotype IV Swine Hepatitis E Virus ORF3 Protein.Veterinary sciences · 2025Article
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Abstract
backgroundSchistosomiasis is a parasitic disease caused by trematodes of the genus Schistosoma. The intravascular worms acquire the nutrients necessary for their survival from host blood. Since all animals are auxotrophic for riboflavin (vitamin B2), schistosomes too must import it to survive. Riboflavin is an essential component of the coenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD); these support key functions of dozens of flavoenzymes.
methodsHere, using a combination of metabolomics, enzyme kinetics and in silico molecular analysis, we focus on the biochemistry of riboflavin and its metabolites in Schistosoma mansoni (Sm).
resultsWe show that when schistosomes are incubated in murine plasma, levels of FAD decrease over time while levels of FMN increase. We show that live schistosomes cleave exogenous FAD to generate FMN and this ability is significantly blocked when expression of the surface nucleotide pyrophosphatase/phosphodiesterase ectoenzyme SmNPP5 is suppressed using RNAi. Recombinant SmNPP5 cleaves FAD with a Km of 178 ± 5.9 µM and Kcat/Km of 324,734 ± 36,347 M
conclusionsThe sequential hydrolysis of FAD by tegumental ecto-enzymes SmNPP5 and SmAP can generate free vitamin B2 around the worms from where it can be conveniently imported by the recently described schistosome riboflavin transporter SmaRT. Finally, we identified in silico schistosome homologs of enzymes that are involved in intracellular vitamin B2 metabolism. These are riboflavin kinase (SmRFK) as well as FAD synthase (SmFADS); cDNAs encoding these two enzymes were cloned and sequenced. SmRFK is predicted to convert riboflavin to FMN while SmFADS could further act on FMN to regenerate FAD in order to facilitate robust vitamin B2-dependent metabolism in schistosomes.
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