Cloning and characterization of Rhodotorula glutinis thymine hydroxylase

Jonathan W. Neidigh, Agus Darwanto, Adides A. Williams, Nathan R. Wall, Lawrence C. Sowers

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Thymine hydroxylase (TH) is a member of the R-ketoglutarate-dependent nonheme iron dioxygenase family that includes a series of DNA repair proteins including alkB. Substantial interest in this family of enzymes derives from their capacity to modify DNA bases and precursors by oxidation. Previously, a sequence has been published for cloned Rhodotorula glutinis TH. However, the minimal reported activity of this enzyme, coupled with inconsistencies with previously published mass spectrometry data, compelled us to reexamine TH. The sequence reported here differs from the previously reported sequence at two amino acid positions and is consistent with previously reported mass spectrometry data. The cloned enzyme characterized in this report displayed substantial activity, indicating that the sequence differences are critical for activity. The substrate selectivity of TH against a series of pyrimidine analogues is consistent with that reported for the wild-type enzyme and, in part, explains the mode of selection of uracil analogues. A preliminary model of the active site has been constructed for the purposes of comparing TH with other members of this family. TH and alkB share in common the capacity to oxidize N-methyl groups. However, TH has the added capacity to oxidize the 5-methyl group of thymine, a property that is potentially important for enzymes that could act on DNA and modify DNA-protein interactions.

Original languageEnglish (US)
Pages (from-to)885-893
Number of pages9
JournalChemical Research in Toxicology
Volume22
Issue number5
DOIs
StatePublished - May 18 2009
Externally publishedYes

ASJC Scopus subject areas

  • Toxicology

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