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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1997-8-5
pubmed:databankReference
pubmed:abstractText
Toxoplasma gondii is an important cause of AIDS-related opportunistic infection, manifest as toxoplasmic encephalitis. The clinical treatment of choice is the synergistic combination of antifolate agents, pyrimethamine and sulphadiazine, of which the latter targets the parasite's dihydropteroate synthase (DHPS) activity. Here, we describe the isolation of the gene encoding this activity in T. gondii. The nucleotide sequence contains an open reading frame interrupted by five introns, which encodes a protein of 664 amino acids with an M(r) of 72991. Sequence analysis revealed that, in addition to DHPS, the predicted protein contains a second enzyme function, hydroxymethyldihydropterin pyrophosphokinase (PPPK). This enzyme immediately precedes DHPS in the folate biosynthetic pathway. The bifunctional arrangement of the T. gondii pppk-dhps gene is the same as that observed in the related protozoan parasite, Plasmodium falciparum, and confirms previous biochemical data that these activities were inseparable. Recently, specific mutations within conserved motifs of the DHPS gene of P. falciparum have been identified which give rise to sulphonamide drug resistance. Analysis of seven clinical isolates of T. gondii did not reveal any similar mutations in this limited sample of organisms that had been subjected to drug pressure.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0166-6851
pubmed:author
pubmed:issnType
Print
pubmed:volume
86
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
37-47
pubmed:dateRevised
2010-8-25
pubmed:meshHeading
pubmed-meshheading:9178266-Amino Acid Sequence, pubmed-meshheading:9178266-Animals, pubmed-meshheading:9178266-Bacteria, pubmed-meshheading:9178266-Base Sequence, pubmed-meshheading:9178266-Cell Line, pubmed-meshheading:9178266-Cloning, Molecular, pubmed-meshheading:9178266-DNA Primers, pubmed-meshheading:9178266-Dogs, pubmed-meshheading:9178266-Gene Library, pubmed-meshheading:9178266-Genes, Protozoan, pubmed-meshheading:9178266-Kidney, pubmed-meshheading:9178266-Molecular Sequence Data, pubmed-meshheading:9178266-Multienzyme Complexes, pubmed-meshheading:9178266-Plasmodium falciparum, pubmed-meshheading:9178266-Polymerase Chain Reaction, pubmed-meshheading:9178266-Recombinant Proteins, pubmed-meshheading:9178266-Saccharomyces cerevisiae, pubmed-meshheading:9178266-Sequence Alignment, pubmed-meshheading:9178266-Sequence Homology, Amino Acid, pubmed-meshheading:9178266-Toxoplasma
pubmed:year
1997
pubmed:articleTitle
Isolation and molecular characterization of the bifunctional hydroxymethyldihydropterin pyrophosphokinase-dihydropteroate synthase gene from Toxoplasma gondii.
pubmed:affiliation
Department of Biochemistry and Applied Molecular Biology, UK.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't