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

Functional characterization of a gene encoding a dual domain for uridine kinase and uracil... 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-α-1-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/uprt1 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. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Molecular Biology Springer Journals

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

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Publisher
Kluwer Academic Publishers
Copyright
Copyright © 2006 by Springer Science+Business Media B.V.
Subject
Life Sciences; Plant Pathology; Biochemistry, general; Plant Sciences
ISSN
0167-4412
eISSN
1573-5028
D.O.I.
10.1007/s11103-006-9101-3
Publisher site
See Article on Publisher Site

Abstract

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-α-1-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/uprt1 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.

Journal

Plant Molecular BiologySpringer Journals

Published: Dec 2, 2006

References

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