Frontiers in Bioscience 9, 1611-1625, May 1, 2004

Abstract

Pyrimidine nucleotides represent one of the most fundamental of cellular components. They are the building blocks for the direct synthesis of DNA and RNA that function in information storage and retrieval within the cell, but they also participate in the metabolism of a large number of other cellular components from sugar interconversion to cellular polysaccharides to glycoproteins and phospholipids. Thus, the metabolism of pyrimidine nucleotides and their intracellular pool sizes influence vast areas of normal cellular metabolism. The first pyrimidine, UMP, is synthesized by a de novo pathway that appears to be mechanistically invariant in all organisms. UMP is then further modified to form other pyrimidines. Breakdown of deoxyribo- and ribonucleic acids, the main sink for pyrimidine nucleotides, allows pyrimidines to be reutilized for resynthesis of these important cellular components. Pyrimidines are salvaged by converting the modified components into the free base, uracil for reutilization. Finally, pyrimidines are degraded into simple cellular metabolites permitting reutilization of nitrogen and carbon from pyrimidine ring systems into cellular metabolic pools. The regulation of pyrimidine metabolism is tightly controlled in plants. Additionally, plants produce toxic secondary metabolites derived from pyrimidines for use as defense compounds.

Metabolomic Responses of Guard Cells and Mesophyll Cells to Bicarbonate

“…Moreover, increased accumulation of adenosine, inosine, and guanosine-derived metabolites in GCs was opposite to their decreased pattern in MCs, indicating their differential responses to elevated CO 2 . Pyrimidine metabolism operates mostly in plastids to provide intermediates for lipid and carbohydrate synthesis [ 63 ]. Decreased pyrimidine levels in GCs at later time-points indicate their possible utilization for the biosynthesis of lipids and sugars.…”

Pyrimidine degradation influences germination seedling growth and production of Arabidopsis seeds

“…Nucleotides are uniquely important since they represent building blocks of genetic information (DNA and RNA), represent major energy carriers, and pyrimidine nucleoside diphosphate sugars are activated intermediates in the synthesis of lipids, sucrose, and cell wall polysaccharides (Moffatt and Ashihara, 2002; Boldt and Zrenner, 2003; Kafer et al , 2004; Zrenner et al , 2006). Furthermore, nucleotides are core elements of cofactors such as NAD, FAD, S -adenosylmethionine, or coenzyme A (CoA), which serve in essential biochemical reactions, such as the synthesis of phospholipids and polysaccharides.…”

The transcriptional response to the olive fruit fly (Bactrocera oleae) reveals extended differences between tolerant and susceptible olive (Olea europaea L.) varieties

“…Among other physiological processes, variation in purine metabolism associates to fruit ripening and to uracil salvage activity during senescence. Moreover, plants produce toxic secondary metabolites from pyrimidines that act as defense compounds [ 40 ]. The “Biosynthesis of antibiotics” KEGG reference pathway ranked first considering the number of enzymatic activities.…”