Pyrimidine metabolism in Tritrichomonas foetus

C. C. Wang, R. Verham, Fu Tzeng Sin Fu Tzeng, S. Aldritt, H. W. Cheng

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Abstract

The anaerobic parasitic protozoa Tritrichomonas foetus is found incapable of de novo pyrimidine biosynthesis by its failure to incorporate bicarbonate, aspartate, or orotate into pyrimidine nucleotides or nucleic acids. Uracil phosphoribosyltransferase in the cytoplasm provides the major pyrimidine salvage for the parasite. Exogenous uridine and cytidine are mostly converted to uracil by uridine phosphorylase and cytidine deaminase in T. foetus prior to incorporation. T. foetus cannot incorporate labels from exogenous uracil or uridine into DNA; it has not detectable dihydrofolate reductase or thymidylate synthetase and is resistant to methotrexate, pyrimethamine, trimethoprim, and 5-bromovinyldeoxyuridine at millimolar concentrations. It has an enzyme thymidine phosphotransferase in cellular fraction pelleting at 100,000 x g that can convert exogenous thymidine to TMP via a phosphate donor such as p-nitrophenyl phosphate or nucleoside 5'-monophosphate. Thymidine salvage in T. foetus is thus totally dissociated from other pyrimidine salvage.

Original languageEnglish
Pages (from-to)2564-2568
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume80
Issue number9 I
Publication statusPublished - 1983
Externally publishedYes

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ASJC Scopus subject areas

  • Genetics
  • General

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