Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.7 (adenine phosphoribosyltransferase)
 692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Independently obtained mutations (apt) of resistance to DAP (2,6-diaminopurine) and MP (6-methylpurine), that affect adenine phosphoribosyltransferase (APRT) in Escherichia coli, are different in their effect on the conversion of several substrates of APRT, such as DAP, MP, MAP (6-methylaminopurine) and adenine, to their nucleotide derivatives. Most of mutants were resistant to DAP and MP, unable to utilize MAP (as purine source) and differed in their ability to uptake adenine from the medium. Among the mutants capable to utilize adenine the following types are found: (1) resistant to DAP and MP, but capable of utilizing MAP, and (2) resistant to DAP, capable of utilizing MAP, but sensitive to MP. The gene apt encoding APRT is located between genes proC and purE; the frequency of cotransduction between proC and several apt mutations is found to be 1.7--2% and purE-apt--to be 5--10.8%. Mutations apt block up the ability of purine-dependent (pur) bacteria lacking purine nucleoside phosphorylase (pup) to use purine ribonucleosides as purine sources. The degree of that blocking depends on the ability of apt mutants to convert adenine to AMP via APRT. These observations confirm our previous data, that the ability of pur pup mutants to use purine ribonucleosides depends on the activity of APRT.
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PMID:[Mutations of resistance to 2,6-diaminopurine and 6-methylpurine that affect adenine phosphoribosyltransferase in Escherichia coli K-12]. 34 74

Love, Samuel H. (Bowman Gray School of Medicine, Wake Forest College, Winston-Salem, N.C.), and Charles N. Remy. Metabolism of methylated purines in Escherichia coli: derepression of purine biosynthesis. J. Bacteriol. 91:1037-1049. 1966.-Various methylated purines were examined for their effects on growth of purine-requiring mutants of Escherichia coli, strains W-11 and B-96, and for their effects on purine biosynthesis. 6-Methylaminopurine and 6-methoxypurine stimulated the accumulation of purine precursor derivatives (ribosyl-5-aminoimidazole and ribosyl-5-amino-4-imidazole carboxamide) beyond their ability to support growth. Information obtained from in vivo and in vitro systems demonstrated that the metabolism of 6-methylaminopurine and 6-methoxypurine utilized identical pathways. The riboside derivatives are formed either by direct ribosidation via nucleoside phosphorylase or, indirectly, by dephosphorylation of the 5'-phosphoribosyl derivatives which are synthesized via adenylate pyrophosphorylase. Information obtained with the aid of strain W-11/DAP (lacking adenylate pyrophosphorylase) demonstrated that both pathways were important to the growing cells. Regardless of the metabolic pathway by which they are synthesized, the ribosyl derivatives are demethylaminated (demethylated) by adenosine deaminase to yield inosine. The final conversion of inosine to inosinic acid via the intermediate formation of hypoxanthine accounts for the net conversion of the methylated bases to inosinic acid. The utilization of the bases is sufficiently rate-limiting to cause derepression of the early enzymes required for the de novo synthesis of purine, thus accounting for the elevated accumulation of purine precursors originally observed.
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PMID:Metabolism of methylated purines in Escherichia coli: derepression of purine biosynthesis. 532 92

Mice null for the Pms2 mismatch repair (MMR) gene exhibit a predisposition to lymphoma, microsatellite repeat instability, and failure of spermatogenesis. To study the role of Pms2 in the maintenance of in vivo genomic integrity in somatic cells, we characterized Aprt mutations in T cells and fibroblasts of 129 x C3H Pms2-/-Aprt+/- mice. The spontaneous frequency of DAP-resistant T lymphocytes, as a consequence of APRT-deficiency, was increased threefold. Point mutation, which accounted for less than 20% of the DAP(r) mutant clones in Pms2+/+ mice, was predominant in the mutant T cell clones from Pms2-/- mice. These point mutations were predominantly TA to CG transitions. Fibroblasts of Pms2-/- mice exhibited only a modest increase in the frequency of clones with point mutations, such that mitotic recombination was still the primary cause of APRT deficiency. Thus, the mutator phenotype as a consequence of PMS2 deficiency is tissue-dependent, which may be related to the tissue-specific tumor proneness of Pms2-/- mice.
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PMID:Loss of heterozygosity and point mutation at Aprt locus in T cells and fibroblasts of Pms2-/- mice. 1197 43