Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:O15067 (FGAM synthetase)
 19 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A study on the oncolytic activity of the L-cysteine derivative L-cysteine, ethyl ester, S-(N-methylcarbamate) monohydrochloride (NSC 303861), revealed that the drug caused complete regression of the MX-1 human mammary tumor xenograft. The compound also exhibited moderate antitumor activity against murine leukemia P388 (T/C value of 169% at a daily dose of 400 mg/kg) and against M5076 sarcoma (T/C value of 135% at a daily dose of 600 mg/kg). The drug was inactive against B16 melanoma, Lewis lung, colon 38 and CD8F1 mammary carcinomas. The compound exhibited significant cytotoxicity against hepatoma 3924A cells in culture (LC50 = 6 microM). Studies on the mechanism of action revealed that the cytotoxicity of the drug could be partially abrogated by protecting hepatoma 3924A cells in culture with L-glutamine. At 6 h after injection of the compound (400 mg/kg) into rats bearing hepatoma 3924A, the pools of L-glutamine and L-glutamate in the tumor decreased to 33% and 71%, respectively, of control levels; the drug selectively inhibited the activities of L-glutamine-requiring enzymes of purine nucleotide biosynthesis, amidophosphoribosyltransferase, FGAM synthase, and GMP synthase, to 21%, 1%, and 69%, respectively, without significantly altering the activities of pyrimidine biosynthetic enzymes, carbamoylphosphate synthase II and CTP synthase. Measurement of the nucleotide concentrations further corroborated the actions of the drug on the purine nucleotide biosynthetic enzyme activities. Drug injection (400 mg/kg) in the hepatoma 3924A-bearing rats reduced the concentrations of IMP in the tumor to 52%, those of total adenylates to 52%, those of total guanylates to 57%, and those of NAD to 73%, without significantly perturbing the pyrimidine nucleotide pools. Studies on the mechanism of action of the L-cysteine derivative suggested that the compound behaved as an L-glutamine antagonist, selectively acting on the enzymes of purine nucleotide biosynthesis.
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PMID:Oncolytic activity and mechanism of action of a novel L-cysteine derivative, L-cysteine, ethyl ester, S-(N-methylcarbamate) monohydrochloride. 234 42

The glutamine antagonists, acivicin (NSC 163501), azaserine (NSC 742), and 6-diazo-5-oxo-L-norleucine (DON) (NSC 7365), are potent inhibitors of many glutamine-dependent amidotransferases in vitro. Experiments performed with mouse L1210 leukemia growing in culture show that each antagonist has different sites of inhibition in nucleotide biosynthesis. Acivicin is a potent inhibitor of CTP and GMP synthetases and partially inhibits N-formylglycineamidine ribotide (FGAM) synthetase of purine biosynthesis. DON inhibits FGAM synthetase, CTP synthetase, and glucosamine-6-phosphate isomerase. Azaserine inhibits FGAM synthetase and glucosamine-6-phosphate isomerase. Large accumulations of FGAR and its di- and triphosphate derivatives were observed for all three antagonists which could interfere with the biosynthesis of nucleic acids, providing another mechanism of cytotoxicity. Acivicin, azaserine, and DON are not potent inhibitors of carbamyl phosphate synthetase II (glutamine-hydrolyzing) and amidophosphoribosyltransferase in leukemia cells growing in culture although there are reports of such inhibitions in vitro. Blockade of de novo purine biosynthesis by these three antagonists results in a "complementary stimulation" of de novo pyrimidine biosynthesis.
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PMID:Cytotoxic mechanisms of glutamine antagonists in mouse L1210 leukemia. 235 67

The purL gene of Escherichia coli encoding the enzyme formylglycinamidine ribonucleotide (FGAM) synthetase which catalyzes the conversion of formylglycinamide ribonucleotide (FGAR), glutamine, and MgATP to FGAM, glutamate, ADP, and Pi has been cloned and sequenced. The mature protein, as deduced by the structural gene sequence, contains 1628 amino acids and has a calculated Mr of 141,418. Comparison of the purL control region to other pur loci control regions reveals a common region of dyad symmetry which may be the binding site for the "putative" repressor protein. Construction of an overproducing strain permitted purification of the protein to homogeneity. N-Terminal sequence analysis and comparison of glutamine binding domain sequences (Ebbole & Zalkin, 1987) confirm the amino acid sequence deduced from the gene sequence. The purified protein exhibits glutaminase activity of 0.02% the normal turnover, and NH3 can replace glutamine as a nitrogen donor with a Km = 1 M and a turnover of 3 min-1 (2% glutamine turnover). The enzyme forms an isolable (1:1) complex with glutamine: t1/2 is 22 min at 4 degrees C. This isolated complex is not chemically competent to complete turnover when FGAR and ATP are added, demonstrating that ammonia and glutamine are not covalently bound as a thiohemiaminal available to complete the chemical conversion to FGAM. hydroxylamine trapping experiments indicate that glutamine is bound covalently to the enzyme as a thiol ester. Initial velocity and dead-end inhibition kinetic studies on FGAM synthetase are most consistent with a sequential mechanism in which glutamine binds followed by rapid equilibrium binding of MgATP and then FGAR. Incubation of [18O]FGAR with enzyme, ATP, and glutamine results in quantitative transfer of the 18O to Pi.
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PMID:Formylglycinamide ribonucleotide synthetase from Escherichia coli: cloning, sequencing, overproduction, isolation, and characterization. 265 70

Formylglycinamidine ribonucleotide (FGAM) synthetase, which catalyzes the conversion of formylglycinamide ribonucleotide (FGAR), glutamine, and ATP to FGAM, ADP, glutamate, and Pi, has been purified to homogeneity (sp act. 0.20 mumol min-1 mg-1) from chicken liver by an alternative procedure to that of Buchanan et al. [Buchanan, J. M., Ohnoki, S., & Hong, B. S. (1978) Methods Enzymol. 51, 193-201] (sp act. 0.12 mumol min-1 mg-1). A variety of new analogues of formylglycinamide ribonucleotide have been prepared in which the formylglycinamide arm (R = CH2NHCHO) has been replaced by R = CH3, CH2OH, CH2Cl, CH2NH3, CH2NHCOCH3, CH2NHCOCH2Cl, CH2NHCO2CH2Ph, and L-CHC-H3NHCHO. These compounds have been characterized by 1H and 13C NMR spectroscopy. With compounds R = CH3, CH2OH, and CH2NHCOCH3 and ATP, in the presence or absence of glutamine, FGAM synthetase catalyzes the production of Pi at 4.5, 48, and 20%, respectively, the rate of production of Pi from formylglycinamide ribonucleotide. Only R = CH2NHCOCH3 causes glutaminase activity as well as ATPase activity and has been shown to be converted to the amidine analogue. Both FGAR (R = CH2NHCHO) and the FGAR analogue (R = CH2NHCHOCH3) in the presence of ATP and FGAM synthetase and in the absence of glutamine form a complex isolable by Sephadex G-50 chromatography. FGAM synthetase is thus highly specific for its formylglycine side chain. [18O]-beta-FGAR was prepared biosynthetically, and FGAM synthetase was shown by 31P NMR spectroscopy to catalyze the transfer of amide 18O to inorganic phosphate.
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PMID:Substrate specificity of formylglycinamidine synthetase. 293 78

The antitumor drug acivicin, L-(alpha S,5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid, irreversibly inactivated in vivo formylglycinamidine ribonucleotide synthetase (FGAM synthetase, EC 6.3.5.3) in transplantable rat hepatoma 3924A while the activity in host liver remained unchanged. At acivicin doses of 1.0 and 5.0 mg/kg body weight, enzyme activity in the hepatoma decreased to 26 and 5%, respectively, after 2 hr. The activity of the in vivo inactivated hepatoma 3924A enzyme could not be restored by gel filtration or 40 hr of dialysis. In the absence of L-glutamine, acivicin in vitro inactivated both liver and hepatoma FGAM synthetase in a time-dependent fashion, with an inactivation constant Kinact = 66 microM and a minimum inactivation half-time T = 1.0 min. In the presence of L-glutamine, competitive inhibition was observed with a Ki = 5 microM. Protection against in vitro inactivation was observed in the presence of 1 mM L-glutamine, suggesting that L-glutamine concentrations are important in the selective toxicity of acivicin on hepatoma cells in vivo. Irreversible inhibition of FGAM synthetase by acivicin is consistent with the view that this antibiotic is an active site-directed affinity analog of L-glutamine and indicates that this enzyme is a sensitive target of acivicin action.
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PMID:In vivo inactivation of formylglycinamidine ribonucleotide synthetase in rat hepatoma. 396 25

The behavior of phosphoribosylformylglycinamidine ( FGAM ) synthetase (EC 6.3.5.3) activity was elucidated in normal and proliferating tissues and in murine and human neoplasms. Enzymic activity was measured in the 100,000 X g crude supernatant fluid prepared from tissue homogenates. The assay was based on coupling FGAM produced to diazotizable aminoimidazole ribonucleotide. In the crude extracts of normal rat liver and hepatoma 3924A, the apparent KmS of FGAM synthetase for formylglycinamide ribonucleotide, adenosine triphosphate and L-glutamine were 0.06, 1.5, and 0.03 mM, respectively. The liver and hepatoma 3924A FGAM synthetases were saturated at formylglycinamide ribonucleotide, adenosine triphosphate, and L-glutamine concentrations of 0.1, 7.0, and 0.5 mM, respectively; both enzymes had a pH optimum of 7.4. In the liver of normal adult rats, the FGAM synthetase activity was 7.2 to 10.7 nmol/hr/mg protein. The synthetase specific activity in hepatomas of slow and medium growth rates increased 1.2- to 2.2-fold, and in rapidly growing hepatomas it was elevated 3.2- to 5-fold over the values of the respective control normal livers. There was a positive correlation between the increase in synthetase activity and hepatoma proliferation rate. In rat tissues of high cell renewal activity, thymus, spleen, and testis, synthetase specific activity was 7.0-, 3.9-, and 3.3-fold higher than that of normal liver. In the 24- and 48-hr regenerating liver, FGAM synthetase specific activity was increased by 1.2- and 1.5-fold, respectively. In 5-day-old differentiating liver, specific activity was 202% of the adult value; when data were expressed per average cell, the activity was 55% of that of the adult liver. The markedly increased activity in the rapidly proliferating hepatomas appears to be more characteristic of neoplastic growth than of normal liver proliferation. FGAM synthetase activity was also increased in human renal cell carcinoma and hepatocellular and colon carcinomas to 1.4-, 2.7-, and 3.8-fold of the activity of the respective homologous normal and host tissues. The synthetase activity in the rapidly proliferating murine Lewis lung carcinoma was 9.6-fold that of the normal lung. The increased activity of FGAM synthetase should confer selective advantages to the cancer cells and marks this glutamine-utilizing enzyme as a potentially important target in the design of chemotherapy.
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PMID:Proliferation-linked increase in phosphoribosylformylglycinamidine synthetase activity (EC 6.3.5.3). 672 84

Formylglycinamide ribonucleotide amidotransferase (FGAR-AT) catalyzes the ATP-dependent conversion of formylglycinamide ribonucleotide (FGAR) and glutamine to formylglycinamidine ribonucleotide (FGAM), ADP, P(i), and glutamate in the fourth step of the purine biosynthetic pathway. In eukaryotes and Gram-negative bacteria, FGAR-AT is encoded by the purL gene as a multidomain protein with a molecular mass of about 140 kDa. In Gram-positive bacteria and archaebacteria FGAR-AT is a complex of three proteins: PurS, PurL, and PurQ. We have determined the structure of FGAR-AT (PurL) from Salmonella typhimurium at 1.9 A resolution using X-ray crystallography. PurL is the last remaining enzyme in the purine biosynthetic pathway to have its structure determined. The structure reveals four domains: an N-terminal domain structurally homologous to a PurS dimer, a linker region, an FGAM synthetase domain homologous to an aminoimidazole ribonucleotide synthetase (PurM) dimer, and a triad glutaminase domain. The domains are intricately linked by interdomain interactions and peptide connectors. The fold common to PurM and the central region of PurL represents a superfamily for which HypE, SelD, and ThiL are predicted to be members. A structural ADP molecule was found bound to a site related to the putative active site by pseudo-2-fold symmetry and two sulfate ions were found at the putative active site. These observations and the structural similarities between PurM and StPurL were used to model the substrates FGAR and ATP in the StPurL active site. A glutamylthioester intermediate was found in the glutaminase domain at Cys1135. The N-terminal (PurS-like) domain is hypothesized to form the putative channel through which ammonia passes from the glutaminase domain to the FGAM synthetase domain.
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PMID:Domain organization of Salmonella typhimurium formylglycinamide ribonucleotide amidotransferase revealed by X-ray crystallography. 1530 31

In the fourth step of the purine biosynthetic pathway, formyl glycinamide ribonucleotide (FGAR) amidotransferase, also known as PurL, catalyzes the conversion of FGAR, ATP, and glutamine to formyl glycinamidine ribonucleotide (FGAM), ADP, P i, and glutamate. Two forms of PurL have been characterized, large and small. Large PurL, present in most Gram-negative bacteria and eukaryotes, consists of a single polypeptide chain and contains three major domains: the N-terminal domain, the FGAM synthetase domain, and the glutaminase domain, with a putative ammonia channel located between the active sites of the latter two. Small PurL, present in Gram-positive bacteria and archaea, is structurally homologous to the FGAM synthetase domain of large PurL, and forms a complex with two additional gene products, PurQ and PurS. The structure of the PurS dimer is homologous with the N-terminal domain of large PurL, while PurQ, whose structure has not been reported, contains the glutaminase activity. In Bacillus subtilis, the formation of the PurLQS complex is dependent on glutamine and ADP and has been demonstrated by size-exclusion chromatography. In this work, a structure of the PurLQS complex from Thermotoga maritima is described revealing a 2:1:1 stoichiometry of PurS:Q:L, respectively. The conformational changes observed in TmPurL upon complex formation elucidate the mechanism of metabolite-mediated recruitment of PurQ and PurS. The flexibility of the PurS dimer is proposed to play a role in the activation of the complex and the formation of the ammonia channel. A potential path for the ammonia channel is identified.
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PMID:Formylglycinamide ribonucleotide amidotransferase from Thermotoga maritima: structural insights into complex formation. 1859 81