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A functional analysis of the pyrimidine catabolic pathway in Arabidopsis
Author(s) -
Zrenner Rita,
Riegler Heike,
Marquard Cathleen R.,
Lange Peter R.,
Geserick Claudia,
Bartosz Caren E.,
Chen Celine T.,
Slocum Robert D.
Publication year - 2009
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2009.02843.x
Subject(s) - uracil , catabolism , biochemistry , arabidopsis , mutant , pyrimidine metabolism , pyrimidine , chemistry , biology , metabolism , enzyme , gene , purine , dna
Summary• Reductive catabolism of pyrimidine nucleotides occurs via a three‐step pathway in which uracil is degraded to β‐alanine, CO 2 and NH 3 through sequential activities of dihydropyrimidine dehydrogenase (EC 1.3.1.2, PYD1), dihydropyrimidinase (EC 3.5.2.2, PYD2) and β‐ureidopropionase (EC 3.5.1.6, PYD3). • A proposed function of this pathway, in addition to the maintenance of pyrimidine homeostasis, is the recycling of pyrimidine nitrogen to general nitrogen metabolism. PYD expression and catabolism of [2‐ 14 C]‐uracil are markedly elevated in response to nitrogen limitation in plants, which can utilize uracil as a nitrogen source. • PYD1 , PYD2 and PYD3 knockout mutants were used for functional analysis of this pathway in Arabidopsis . pyd mutants exhibited no obvious phenotype under optimal growing conditions. pyd2 and pyd3 mutants were unable to catabolize [2‐ 14 C]‐uracil or to grow on uracil as the sole nitrogen source. By contrast, catabolism of uracil was reduced by only 40% in pyd1 mutants, and pyd1 seedlings grew nearly as well as wild‐type seedlings with a uracil nitrogen source. These results confirm PYD1 function and suggest the possible existence of another, as yet unknown, activity for uracil degradation to dihydrouracil in this plant. • The localization of PYD‐green fluorescent protein fusions in the plastid (PYD1), secretory system (PYD2) and cytosol (PYD3) suggests potentially complex metabolic regulation.