Disease relevance of UMP

• The substrate preference of recombinant Escherichia coli thymidylate synthase (TS) has been altered from 2'-deoxyuridylate (dUMP) to 2'-deoxycytidylate (dCMP) by site-directed mutagenesis of the codon for Asn177, which was changed to aspartic acid [1].
• The interaction of Lactobacillus casei thymidylate synthase (TS) with 10-propargyl-5,8-dideazafolate (NPQ) in the presence of 2'-deoxyuridylate (dUMP) has been investigated [2].
• Observations on the mechanisms underlying the defective methylation of deoxyuridylate in kwashiorkor [3].
• Cloning, expression, purification, and characterization of 2'-deoxyuridylate hydroxymethylase from phage SPO1 [4].
• The formation and stability of the covalent ternary complex formed between thymidylate synthase (E.C. 2.1.1.45), 5-fluoro 2'-deoxyuridylate (FdUMP) and 5,10-methylenetetrahydrofolate (CH2-H4PteGlu) has been examined in cytosols derived from xenografts of human colon adenocarcinomas [5].

High impact information on UMP

• An uncommon nucleotide conformation shown by molecular structure of deoxyuridine-5'-phosphate and nucleic acid stereochemistry [6].
• Among the residues that form the dCMP binding site, those interacting with the sugar and phosphate are arranged in a configuration similar to the deoxyuridylate binding site of thymidylate synthases [7].
• Biochemical determinants of tumor sensitivity to 5-fluorouracil: ultrasensitive methods for the determination of 5-fluoro-2'-deoxyuridylate, 2'-deoxyuridylate, and thymidylate synthetase [8].
• The structure of the 2'-deoxyuridine-5'-monophosphate and 10-propargyl-5,8-dideazafolate folate analog complex identifies both ligands in orientations favorable for the initiation of catalysis and resembles the productive complex [9].
• BACKGROUND: Thymidylate synthase (TS; EC 2.1.1.45) catalyzes the reductive methylation of 2'-deoxyuridine-5'-monophosphate (dUMP) by 5,10-methylene-5,6,7,8-tetrahydrofolate (CH2H4folate) to produce 2'-deoxythymidine-5'-monophosphate (dTMP) and 7,8-dihydrofolate (H2folate) [10].

Chemical compound and disease context of UMP

• The structure of a polyglutamyl cofactor analog bound in ternary complex with deoxyuridine monophosphate (dUMP) and Escherichia coli TS reveals how the polyglutamyl moiety is positioned in TS and accounts in a qualitative way for the binding contributions of the different individual glutamate residues [11].
• We have investigated the role of invariant arginine 166, one of four arginines that contact the dUMP phosphate, using site-directed mutagenesis, X-ray crystallography, and TS from Escherichia coli [12].

Biological context of UMP

• DNA fragmentation and cytotoxicity from increased cellular deoxyuridylate [13].
• This study showed changes in the TS enzyme kinetics during the induction of doxorubicin resistance in both SW-1573 variants, resulting in 2-fold lower Km values for 2'-deoxyuridine-5'-monophosphate (dUMP) in both resistant variants compared to the parental cell line [14].
• The thymidylate synthase gene ( TYMS or TS) encodes a tightly regulated enzyme that catalyzes the conversion of deoxyuridylate to thymidylate, and contains a tandem repeat polymorphism that affects expression of the enzyme [15].
• Intracellular dUMP levels following 24 h D1694 (IC50) exposure increased 7-fold [16].
• Upstream of the mch gene two open reading frames were recognized, one encoding for a 25-kDa protein with sequence similarity to deoxyuridylate hydroxymethylase and the other encoding for a 34.6-kDa protein with sequence similarity to cobalamin-independent methionine synthase (MetE) [17].

Anatomical context of UMP

• The apparent Michaelis-Menten constant (Km) for deoxyuridine-5'-monophosphate and inhibition constant (Ki) for 5-fluoro-deoxyuridine-5'-monophosphate, measured by whole-cell enzyme assay, appear to be similar for the wild-type and revertant cell lines [18].
• The bone marrow cells gave a normal deoxyuridine suppressed value, indicating that there was no impairment of the methylation of deoxyuridylate [19].

Associations of UMP with other chemical compounds

• Fluorodeoxyuridylate (FdUMP) was assayed by isotope dilution of [3H]FdUMP binding to bacterial TS; free and total TS was determined by [3H]FdUMP binding; and deoxyuridylate (dUMP) was assayed by conversion to [14C]thymidylate [20].
• The structural evidence reveals that upon binding cofactor analogue and forming a covalent bond from the nucleophilic cysteine to the substrate, dUMP, at one active site, PcTS undergoes a conformational change that renders the opposite monomer incapable of forming a covalent bond or binding a molecule of cofactor analogue [21].
• Following electroporation, cells were shown to be fully functional as monitored by the incorporation of deoxyuridylate, after conversion to thymidylate, into DNA [22].
• Invariant arginine 179, one of four arginines that are conserved in all thymidylate synthases (TS) and that bind the phosphate moiety of the substrate 2'-deoxyuridine-5'-monophosphate (dUMP), can be altered even to a negatively charged glutamic acid with little effect on kcat [23].
• The assay is based on the separation of the substrate, deoxyuridylate (dUMP), and its product, deoxythymidylate (dTMP), on a LiChrosorb RP-8 reversed-phase column with 44 mM triethylammonium phosphate (pH 7.0) as mobile phase and a flow-rate of 1.0 ml/min [24].

Gene context of UMP

• 5,8 DideazaisoPteGlu3 bound more tightly to thymidylate synthase than dihydrofolate reductase as indicated by Kis of 0.09 and 0.7 microM when deoxyuridylate and dihydropteroylglutamate, respectively, were the variable substrates [25].
• Studies on the interaction with thymidylate synthase of analogues of 2'-deoxyuridine-5'-phosphate and 5-fluoro-2'-deoxyuridine-5'-phosphate with modified phosphate groups [26].
• RESULTS: We report the crystal structure of E. coli TS in ternary complex with dUMP and BW1843U89 at 2.0 A resolution [27].
• Validation of this approach will involve a comparison of the observed gene expression levels to TS protein levels obtained by tissue homogenization assays of TS, tetrahydrofolate, 5,10-methylenetetrahydrofolate, 2'-deoxyuridine-5'-monophosphate and 5-fluoro-2'-deoxyuridylate (FdUMP), by established [3H]FdUMP ligand-binding assays [28].
• The SO4-.-induced oxidation of 2'-deoxyuridine-5'-phosphate, uridine-5'-phosphate and thymidine-5'-phosphate. An ESR study in aqueous solution [29].

Analytical, diagnostic and therapeutic context of UMP

• It is suggested that combination chemotherapy with fluorinated pyrimidines and inhibitors of deoxyuridylate synthesis may improve the therapeutic response to these drugs [30].
• Radiolytic products such as deoxyuridine-monophosphate (dUMP), uracil and bromo-uracil (Br-uracil) were isolated using high performance liquid chromatography [31].
• The R166Q mutant was crystallized in the presence of dUMP and a structure determined to 2.9 A resolution, but neither the ligand nor the sulfate from the crystallization buffer was found in the active site [12].

References