Functional characterization of a gene encoding a dual domain for uridine kinase and uracil phosphoribosyltransferase in Arabidopsis thaliana

Plant Mol Biol. 2007 Mar;63(4):465-77. doi: 10.1007/s11103-006-9101-3.


Uridine kinase (UK) and uracil phosphoribosyltransferase (UPRT) are enzymes catalyzing the formation of uridine 5'-monophosphate (UMP) from uridine and adenine 5'-triphosphate (ATP) and from uracil and phosphoribosyl-alpha-l-pyrophosphate (PRPP), respectively, in the pyrimidine salvage pathway. Here, we report the characterization and functional analysis of a gene AtUK/UPRT1 from Arabidopsis thaliana. Sequencing of an expressed sequence tag clone of this gene revealed that it contains a full-length open reading frame of 1461 nucleotides and encodes a protein with a molecular mass of approximately 53 kDa. The sequence analysis revealed that the N-terminal region of AtUK/UPRT1 contains a UK domain and the C-terminal region consists of a UPRT domain. Expression of AtUK/UPRT1 in upp and upp-udk mutants of Escherichia coli supplied with 5-fluorouracil (5-FU) and 5-fluorouridine (5-FD) led to growth inhibition. Identical results were obtained with 5-FD and 5-FU treatments when the UK and UPRT domains were separated by the introduction of translation initiation and stop codons prior to complementation into the upp-udk and upp mutants. These results suggest that the AtUK/UPRT1 product can use uracil and uridine as substrates for the production of UMP. We also investigated the function of AtUK/UPRT1 in an Arabidopsis mutant. The wild-type Arabidopsis plants showed drastic growth retardation when they were treated with 5-FU and 5-FD while the growth of atuk/uprtl mutant plants was not significantly affected. These findings confirm that AtUK/UPRT1 has a dual role in coding for both uridine kinase and uracil phosphoribosyltransferase that form UMP through the pyrimidine salvage pathway in Arabidopsis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics*
  • Arabidopsis Proteins / genetics
  • Base Sequence
  • DNA Primers
  • DNA, Plant / genetics
  • Escherichia coli / genetics
  • Expressed Sequence Tags
  • Genes, Reporter
  • Molecular Sequence Data
  • Pentosyltransferases / genetics*
  • Sequence Alignment
  • Transfection
  • Uridine Kinase / genetics*


  • Arabidopsis Proteins
  • DNA Primers
  • DNA, Plant
  • Pentosyltransferases
  • uracil phosphoribosyltransferase
  • Uridine Kinase

Associated data

  • GENBANK/AY089970