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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By promoter fusion to the galK gene and comparative S1 analysis we investigated the in vivo regulation of transcription of the dnaQ gene which encodes the epsilon-subunit of the DNA polymerase III holoenzyme carrying the 3'----5' exonucleolytic proofreading function. Induction of a mutagenic stress situation by treatment with the base analogue 2-aminopurine (2-AP) leads to an increase in dnaQ transcription. S1 mapping analysis of the two dnaQ transcripts revealed a differential promoter activation for this 2-AP induced increase in dnaQ transcription. In addition, a similar galK promoter fusion with the dnaN gene coding for the beta-subunit of the DNA polymerase III holoenzyme revealed that dnaN transcription is also 2-AP inducible as judged by galactokinase activity. This is the first evidence for the inducibility of dnaQ gene expression (and possibly of other genes of the DNA polymerase II holoenzyme) and is discussed in relation to DNA repair mechanisms.
Mol Gen Genet 1988 Jan
PMID:Expression of the Escherichia coli dnaQ (mutD) gene is inducible. 283 Apr 59

2-aminopurine (2-AP) and 5-bromouracil, strong mutagens of base analog type, were found to induce efficiently the alleviation of I type restriction in Escherichia coli. 2-AP induced restriction alleviation occurs in recA, lexA and mut- mutants, but no additional relief of restriction is registered in dam-bacteria in the presence of sublethal 2-AP concentrations. 2-AP specifically alleviates I type restriction in Escherichia coli (EcoA, EcoB, EcoD, and EcoK) and does not affect restriction systems of II (EcoRI) and III (EcoP1) types. We suggest that 2-AP-induced mismatches and other replication errors may be signals inducing restriction alleviation in Escherichia coli.
Mol Gen Mikrobiol Virusol 1987 Dec
PMID:[Weakening of type I restriction in E. coli: the effect of 2-aminopurine and 5-bromouracil]. 283 97

The enzymes that catalyse the salvage of purines in Entamoeba histolytica trophozoites have been surveyed. Adenine deaminase (EC 3.5.4.2), adenosine deaminase (EC 3.5.4.4), guanine deaminase (EC 3.5.4.3), adenine phosphoribosyltransferase (PRTase) (EC 2.4.2.7), xanthine PRTase (EC 2.4.2.22) and hypoxanthine PRTase (EC 2.4.2.8) were all detected in cell homogenates but only at low activities, whereas AMP deaminase (EC 3.5.4.6) and guanine PRTase (EC 2.4.2.8) were not found. Phosphorylases (EC 2.4.2.1) active in both anabolic and catabolic directions were present and all nucleosides tested were phosphorylated by kinases (EC 2.7.1.15, EC 2.7.1.20, EC 2.7.1.73). 3'-Nucleotidase (EC 3.1.3.6) and 5'-nucleotidase (EC 3.1.3.5) were found, the former being mainly particulate. Nucleotide interconversion enzymes (adenylosuccinate lyase, EC 4.3.2.2; adenylosuccinate synthetase, EC 6.3.4.4; IMP dehydrogenase, EC 1.2.1.14; GMP synthetase, EC 6.3.5.2 and GMP reductase, EC 1.6.6.8) were not detected. The results suggest that in E. histolytica the main route of nucleotide synthesis is from the individual bases through the actions of phosphorylases and kinases.
Mol Biochem Parasitol 1986 Apr
PMID:Purine-metabolising enzymes in Entamoeba histolytica. 287 91

The EcoK restriction of unmodified phage lambda is 1000-fold alleviated in Escherichia coli grown in the presence of base analogs 2-aminopurine (2AP) and 5-bromouracil (5BU). 2AP treatment of bacteria affects specifically the type I restriction systems (EcoA, EcoB, EcoD and EcoK) and does not influence type II (EcoRI) and type III (EcoP1) restriction. 2AP-induced alleviation of restriction occurs in bacteria which are deficient in the SOS response (recA and lexA) and mismatch repair (mutH, mutL and mutS) and can be distinguished from the alleviation of restriction observed in dam- strains. We suggest that mismatches induced by 2AP and 5BU may function as an inducing signal for the alleviation of restriction observed in the presence of base analogs.
Mol Gen Genet 1988 Oct
PMID:2-Aminopurine and 5-bromouracil induce alleviation of type I restriction in Escherichia coli: mismatches function as inducing signals? 297 82

Diploid Saccharomyces cerevisiae cells heterozygous for the mating type locus (MATa/MAT alpha) undergo meiosis and sporulation when starved for nitrogen in the presence of a poor carbon source such as potassium acetate. Diploid yeast adenine auxotrophs sporulated well at high cell density (10(7) cells per ml) under these conditions but failed to differentiate at low cell density (10(5) cells per ml). The conditional sporulation-deficient phenotype of adenine auxotrophs could be complemented by wild-type yeast cells, by medium from cultures that sporulate at high cell density, or by exogenously added adenine (or hypoxanthine with some mutants). Adenine and hypoxanthine in addition to guanine, adenosine, and numerous nucleotides were secreted into the medium, each in its unique temporal pattern, by sporulating auxotrophic and prototrophic yeast strains. The major source of these compounds was degradation of RNA. The data indicated that differentiating yeast cells cooperate during sporulation in maintaining sufficiently high concentrations of extracellular purines which are absolutely required for sporulation of adenine auxotrophs. Yeast prototrophs, which also sporulated less efficiently at low cell density (10(3) cells per ml), reutilized secreted purines in preference to de novo-made purine nucleotides whose synthesis was in fact inhibited during sporulation at high cell density. Adenine enhanced sporulation of yeast prototrophs at low cell density. The behavior of adenine auxotrophs bearing additional mutations in purine salvage pathway genes (ade apt1, ade aah1 apt1, ade hpt1) supports a model in which secretion of degradation products, uptake, and reutilization of these products is a signal between cells synchronizing the sporulation process.
Mol Cell Biol 1988 Dec
PMID:Evidence for cooperation between cells during sporulation of the yeast Saccharomyces cerevisiae. 307 77

The translational efficiency of mRNA molecules transcribed from plasmid DNA transfected into COS-1 monkey cells can be increased 10- to 20-fold by the coexpression of the adenovirus virus-associated RNAs I and II. Experiments described here demonstrate a similar increase in translational efficiency by the addition of 2-aminopurine, an inhibitor of double-stranded RNA-activated protein kinase, to the culture medium. Both virus-associated RNA and 2-aminopurine presumably exert their effect by alteration of the functional level of eucaryotic initiation factor-2. The translational stimulation mediated by both means is shown to be restricted to the plasmid-derived mRNAs because there is no qualitative or quantitative alteration in host protein synthesis. The results are consistent with models invoking a localized activation of double-stranded RNA-activated kinase leading to a translational block.
Mol Cell Biol 1987 Apr
PMID:Translational control mediated by eucaryotic initiation factor-2 is restricted to specific mRNAs in transfected cells. 360 Jun 37

Adenine phosphoribosyltransferase (APRT) (EC 2.4.2.7) pseudorevertant cell lines were isolated under selective conditions requiring adenine salvage for survival; yet they were found to be deficient in measurable APRT activity and resistant to the purine analog 2'6'-diaminopurine (DAP) (M.S. Turker, J. A. Tischfield, P. Rabinovitch, P.J. Stambrook, J.J. Trill, A.C. Smith, C.E. Ogburn, and G.M. Martin, manuscript in preparation). Adenine salvage was examined in two APRT pseudorevertant cell lines, their two APRT homozygous deficient parental cell lines, and a genotypic APRT revertant cell line (i.e., one with measurable APRT activity and DAP sensitivity). Adenine accumulation was observed in both revertant phenotypes and was demonstrated by high-performance liquid chromatography to be linked with adenine metabolism. The ability to salvage adenine declined substantially in the pseudorevertant cell lines when they were removed from selective media containing inhibitors of de novo 5'-AMP synthesis (alanosine and azaserine); for one pseudorevertant cell line this decline was accelerated by the addition of DAP to the medium. The readdition of alanosine or azaserine to the growth medium of the pseudorevertant lines induced adenine salvage to its previous levels. An APRT-like cross-reacting material was found in the pseudorevertant cell lines, although its relationship to adenine salvage is unknown. A low level of constitutive adenine salvage was found in the parental APRT-deficient lines, and it was also possible to induce adenine salvage in these cell lines. These findings suggest a novel regulatory mechanism for adenine salvage.
Mol Cell Biol 1985 Oct
PMID:Induction of adenine salvage in mouse cell lines deficient in adenine phosphoribosyltransferase. 383 81

Culture forms of Trypanosoma cruzi are incapable of synthesizing purines de novo from formate, glycine, or serine and require an exogenous purine for growth. Adenine, hypoxanthine, guanine, xanthine and their respective ribonucleosides are equal in their abilities to support growth. Radiolabeled purine bases, with the exception of guanine, are stable and are converted to their respective ribonucleotides directly by phosphoribosyltransferase activity. Guanine is both converted to its ribonucleotide and deaminated to xanthine. Purine nucleosides are not hydrolysed to any extent but are converted to their respective ribonucleotides. This conversion may involve a rete-limiting ribonucleoside cleaving activity or a purine nucleoside kinase or phosphotransferase activity. The apparent order of salvage efficiency for the bases and their respective ribonucleosides is adenine greater than hypoxanthine greater than guanine greater than xanthine.
Mol Biochem Parasitol 1981 Jul
PMID:Purine metabolism in Trypanosoma cruzi. 616 62

To determine the molecular basis for the temperature-sensitivity of pure rho RNA-dependent ATPase from Escherichia coli mutant rho-115 cells, we investigated mutant rho binding to [3H] polyC as measured by retention on nitrocellulose filters. Complexes of wild-type rho and polyC incubated at 37 degrees C and 45 degrees C were similarly stable. At 37 degrees C mutant rho-polyC binary complexes were inactivated at a slightly faster rate than complexes with wild-type rho. Upon shift to 45 degrees C the quantity of rho-115 bound to polyC declined immediately, resulting in one-fifth of the quantity of complexes observed at 37 degrees C. Shift back to 37 degrees C restored the level of observed complexes by two-fold. The inclusion of ATP or the analogue beta-gamma methylene ATP during 45 degrees C incubation resulted in stable mutant rho-polyC complexes. The hydrolysis product ADP was also effective in stabilizing binary complexes at 45 degrees C but this effect was observed with an order of magnitude more ADP than ATP. Adenine, adenosine, AMP or Pi had no stabilizing effect. We conclude that the mutant rho-115 protein exhibits a structural instability as a result of binding RNA. Furthermore ATP confers a wild-type phenotype upon rho-115 protein, probably as a result of conformational change due to binding of this compound. The effect of ATP on the stability of mutant rho-polyC binary complexes supports the model of ATP modulation of rho-RNA interaction proposed by Galluppi and Richardson (1980).
Mol Gen Genet 1982
PMID:Temperature-sensitive mutant rho-115 rho-RNA binary complexes, and stabilization by substrates and analogues. 621 99

The survival of UV-irradiated lambda phages is increased when host bacteria are grown in the presence of the base analogue 2-aminopurine (2AP) before infection. This increase in survival, which we have called "2AP-reactivation" depends upon the concentration of 2AP and the time of exposure to 2AP. 2AP-reactivation can be distinguished from Weigle-reactivation in that it is not accompanied by an increase in mutagenesis, does not act on the single-stranded DNA bacteriophage phi X174, and occurs in recA and lexA bacteria. 2AP reactivation does not appear to involve known systems of recombinational repair, as it occurs in recB and recF bacteria, or excision repair, as it occurs in uvrA and uvrB bacteria. It is however dependent upon DNA polymerase I.
Mol Gen Genet 1982
PMID:2-aminopurine induced DNA repair in E. coli. 621 2


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