Potential antifolate resistance determinants and genotypic variation in the bifunctional dihydrofolate reductase-thymidylate synthase gene from human and bovine isolates of Cryptosporidium parvum

Vásquez, John R.; Goozé, Lisa; Kim, K; Gut, Jiří; Petersen, Carolyn; Nelson, Richard G.

doi:10.1016/0166-6851(96)02647-3

Cited by 100 publications

(57 citation statements)

References 26 publications

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“…More recently, random amplified polymorphic DNA (RAPD) markers have revealed two distinct groups of human C. parvum isolates, one containing most human isolates and the other containing some human isolates and all animal isolates (Morgan et al 1995), indicating the possibility of zoonotic infection. Similar results have been obtained by sequence data or PCR-RFLP analysis of a repetitive sequence (Bonnin et al 1996), bifunctional dihydrofolate reductase thymidylate synthase (DHFR) (Vasquez et al 1996), rRNA repeats (Carraway et al 1996), polythreonine motifs (Carraway et al 1997), oocyst wall protein (COWP) gene (Spano et al 1997), and thrombospondin anonymous protein-2 (TRAP-C2) gene (Peng et al 1997 Sulaiman et al unpub. data).…”

Section: Cryptosporidium Parvum Genotypessupporting

confidence: 66%

Species and Strain-specific Typing of Cryptosporidium Parasites in Clinical and Environmental Samples

Xiao

Sulaiman²,

Fayer³

et al. 1998

Mem. Inst. Oswaldo Cruz

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Section: Cryptosporidium Parvum Genotypessupporting

confidence: 66%

Species and Strain-specific Typing of Cryptosporidium Parasites in Clinical and Environmental Samples

Xiao

Sulaiman²,

Fayer³

et al. 1998

Mem. Inst. Oswaldo Cruz

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“…Our analysis of UK-UPRT provides molecular evidence of an algal or ''plant-like'' gene in the plastid-less genus Cryptosporidium. This evidence, combined with the presence of the bifunctional enzyme dihydrofolate reductase-thymidylate synthase, DHFR, in C. parvum (33) and other apicomplexans provides an additional phylogenetic link between the Apicomplexa and plants. Whether the presence of both fused genes in these lineages indicates monophyly (21, 22) or multiple independent gene transfers (34) remains to be determined.…”

Section: Resultsmentioning

confidence: 99%

Gene transfer in the evolution of parasite nucleotide biosynthesis

Striepen

Pruijssers

Huang

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

194

198

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Nucleotide metabolic pathways provide numerous successful targets for antiparasitic chemotherapy, but the human pathogen Cryptosporidium parvum thus far has proved extraordinarily refractory to classical treatments. Given the importance of this protist as an opportunistic pathogen afflicting immunosuppressed individuals, effective treatments are urgently needed. The genome sequence of C. parvum is approaching completion, and we have used this resource to critically assess nucleotide biosynthesis as a target in C. parvum. Genomic analysis indicates that this parasite is entirely dependent on salvage from the host for its purines and pyrimidines. Metabolic pathway reconstruction and experimental validation in the laboratory further suggest that the loss of pyrimidine de novo synthesis is compensated for by possession of three salvage enzymes. Two of these, uridine kinase-uracil phosphoribosyltransferase and thymidine kinase, are unique to C. parvum within the phylum Apicomplexa. Phylogenetic analysis suggests horizontal gene transfer of thymidine kinase from a proteobacterium. We further show that the purine metabolism in C. parvum follows a highly streamlined pathway. Salvage of adenosine provides C. parvum's sole source of purines. This renders the parasite susceptible to inhibition of inosine monophosphate dehydrogenase, the rate-limiting enzyme in the multistep conversion of AMP to GMP. The inosine 5 monophosphate dehydrogenase inhibitors ribavirin and mycophenolic acid, which are already in clinical use, show pronounced anticryptosporidial activity. Taken together, these data help to explain why widely used drugs fail in the treatment of cryptosporidiosis and suggest more promising targets.Cryptosporidium parvum ͉ horizontal gene transfer ͉ drug target ͉ thymidine kinase ͉ IMPDH

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“…Although, in most species, including humans, TS and DHFR activities reside on separate monofunctional enzymes, several protozoan parasites have these activities expressed on a single polypeptide chain that comprises a bifunctional thymidylate synthasedihydrofolate reductase (TS-DHFR) 2 enzyme (4 -8). One of these protozoa, Toxoplasma gondii, is prevalent and problematic in the United States (8). Opportunistic toxoplasmosis is often associated with the onset of the clinical AIDS syndrome and is a primary cause of suffering and death in AIDS patients (6).…”

mentioning

confidence: 99%

Mechanistic Characterization of Toxoplasma gondiiThymidylate Synthase (TS-DHFR)-Dihydrofolate Reductase

Johnson

Hinz

Atreya

et al. 2002

Journal of Biological Chemistry

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This study describes the use of rapid transient kinetic methods to characterize the bifunctional thymidylate synthase-dihydrofolate reductase (TS-DHFR) enzyme from Toxoplasma gondii. In addition to elucidating the detailed kinetic scheme for this enzyme, this work provides the first direct kinetic evidence for the formation of a TS intermediate and for half-sites TS reactivity in human and Escherichia coli monofunctional TS and in T. gondii and Leishmania major bifunctional TS-DHFR. Comparison of the T. gondii TS-DHFR catalytic mechanism to that of the L. major enzyme reveals the mechanistic differences to be predominantly in DHFR activity. Specifically, TS ligand induced domain-domain communication involving DHFR activation is observed only in the L. major enzyme and, whereas both DHFR activities involve a rate-limiting conformational change, the change occurs at different positions along the kinetic pathway.

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Potential antifolate resistance determinants and genotypic variation in the bifunctional dihydrofolate reductase-thymidylate synthase gene from human and bovine isolates of Cryptosporidium parvum

Cited by 100 publications

References 26 publications

Species and Strain-specific Typing of Cryptosporidium Parasites in Clinical and Environmental Samples

Species and Strain-specific Typing of Cryptosporidium Parasites in Clinical and Environmental Samples

Gene transfer in the evolution of parasite nucleotide biosynthesis

Mechanistic Characterization of Toxoplasma gondiiThymidylate Synthase (TS-DHFR)-Dihydrofolate Reductase

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