On the Catabolism of Deoxyribonucleosides in Cells and Cell Extracts of <i>Escherichia coli</i>

Munch‐Petersen, Agnete

doi:10.1111/j.1432-1033.1968.tb00465.x

Cited by 84 publications

(49 citation statements)

References 31 publications

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“…coli requires that both thymidine phosphorylase and purine nucleoside phosphorylase are active [21].…”

Section: And Discussionmentioning

confidence: 99%

Inability of Escherichia coliB to Incorporate Added Deoxycytidine, Deoxyadenosine, and Deoxyguanosine into DNA

Karlström

1970

European Journal of Biochemistry

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It is known that Escherichia coli can incorporate labeled thymidine into its DNA, but it has not been previously possible to measure the incorporation of the other deoxyribonuclcosides deoxycytidine, deoxyadenosine, and deoxyguanosine because of degradation of these com-The present experiments utilize a mutant of E . coli B lacking deoxyribonucleoside-catabolizing enzymes. This strain, OK441, has mutations affecting the following enzymes : thymidine phosphorylase, purine nucleoside phosphorylase, cytidine deaminase, and adenosine deaminase.The results with OK441 show that E . coZi, in contrast t o lactobacilli and mammalian cells, does not incorporate any deoxyribonucleoside other than thymidine into its DNA. E . coli may be unable t o phosphorylate deoxycytidine, deoxyadenosine, and deoxyguanosine. I n agreement with this suggestion, only thymidine kinase but no other deoxyribonucleotide kinase could be detected in extracts of OK441. pounds.When radioactively labeled thymidine is added to the medium of growing Escherichia coli, label is incorporated into DNA. With [S]. It contains mutations affecting the cytidine and adenosine deaminases, which degrade deoxycytidine and deoxyadenosine, respectively. It also contains mutations affecting thymidine phosphorylase, which degrades thymidine, and purine nucleoside phosphorylase which attacks deoxyadenosine and deoxyguanosine.The experiments demonstrate that thymidine is the only deoxyribonucleoside that is incorporated at a n appreciable rate into DNA. EXPERIMENTAL PROCEDURES MaterialsChemicals were from the same sources as previously described [8]. All 14C-labeled deoxyribonucleosides were from the Radiochemical Centre (Amersham, Buckinghamshire, England) and all were uniformly labeled except thymidine, which was labeled at C-2. Glass filters were Whatman GF81. XtrainsAll bacterial strains were derivatives of E . coli R .Thcir origins are given in Table 1. The symbols cdd, add, pup, and tpp refer t o loss of cytidine deaminase, adenosine deaminase, purine nucleoside phosphorylase, and thymidine phosphorylase, respectively. The mutation tZr-4 (thymine low requirement) [ill probably affects deoxyribose I ,5-phosphate mutase as it does not cause sensitivity t o deoxyribosides /12,13].

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“…coli requires that both thymidine phosphorylase and purine nucleoside phosphorylase are active [21].…”

Section: And Discussionmentioning

confidence: 99%

Inability of Escherichia coliB to Incorporate Added Deoxycytidine, Deoxyadenosine, and Deoxyguanosine into DNA

Karlström

1970

European Journal of Biochemistry

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“…Thymidine phosphorylase activity was determined by the spectrophotometric measurement of the phosphate-dependent cleavage of thymidine (13), and enzyme units were as thus defined. Assays were performed on sonicates of log-phase cells grown either under inducing conditions (TY broth containing 8 mM thymidine) or under noninducing conditions (VB minimal medium without thymidine), as stated.…”

Section: Materuils and Methodsmentioning

confidence: 99%

De novo synthesis of thymidylate via deoxycytidine in dcd (dCTP deaminase) mutants of Escherichia coli

Weiss

Wang

1994

J Bacteriol

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dcd (dCTP deaminase) mutants of Escherichia coli were reported not to require thymidine for growth even though most of the thymidylate that is synthesized de novo arises from cytosine nucleotides through a pathway involving dCTP deaminase. We found, however, that the fresh introduction of dcd mutations into many strains of E. coli produced a requirement for thymidine for optimum aerobic growth, but the mutants readily reverted to prototrophy via mutations in other genes. One such mutation was in deoA, the gene for deoxyuridine phosphorylase. However, a dcd deo mutant became thymidine dependent once again if a cdd mutation (affecting deoxycytidine deaminase) were introduced. The results indicate that dcd mutants utilize an alternative pathway of TMP synthesis in which deoxycytidine and deoxyuridine are intermediates. A cdd mutation blocks the pathway by preventing the conversion of deoxycytidine to deoxyuridine, whereas a deoA mutation enhances it by sparing deoxyuridine from catabolism. The deoxycytidine must arise from dCTP or dCDP via unknown steps. It is not known to what extent this pathway is utilized in wild-type cells, which, unlike the ded mutants, do not accumulate dCTP.In Escherichia coli, dUTP is an obligatory precursor for the biosynthesis of thymidylate ( Fig. 1) (14,24). Previous studies in E. coli and Salmonella typhimurium suggested that under aerobic conditions, only about 25% of the dUTP is synthesized in a manner analogous to that of the other deoxynucleoside triphosphates, i.e., by the phosphorylation of dUDP that is generated by the reduction of UDP. The remaining 75% of dUTP is produced by dCTP deaminase (15), the product of the dcd gene (27). Accordingly, dcd mutants were noted to have a reduced TTP pool (16) and an increased sensitivity to 5-bromodeoxyuridine (BrdUrd) (7). This sensitivity is consistent with a defect in the synthesis de novo of thymidylate, which would compete with the analog for incorporation into DNA. Nevertheless, dcd mutants have been described as prototrophs (5,14,16,17); they do not require thymidine for growth. Although some dcd mutants with extensive deletions grew slowly and manifested some filamentation, these effects were thymidine independent (16). These results might lead us to the unexpected conclusion that the pathway by which most TMP is synthesized is dispensable. In this study, we examine alternative pathways that may be used by dcd mutants. MATERUILS AND METHODSBacterial strains. The strains used in this study are listed in Table 1. Additional dcd and deoA derivatives were constructed from these strains in the following way. dcd-12::Tnl0dkan was introduced by P1-mediated transduction from BW1040 with selection for kanamycin resistance. deoA22 was introduced by cotransduction with thr-34::TnlO from BW933 with selection for tetracycline resistance. deoA22 transductants were detected by their inability to use thymidine as the sole carbon source. (26) containing thiamine (1 ,ug/ml); glucose (at 0.4%) was used routinely as the carbon source. Amino acids wer...

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“…(Ling et al, 1994) UPase is induced by both uridine and adenosine. In this study, we showed that UPase from E. aerogenes is induced by adenosine, cytidine, uridine and their corresponding nucleotides using Medium 2 (Munch-Petersen, 1968;Robertson et al, 1970;Hammer-Jespersen et al, 1971;Vita et al, 1983). TPases from E. coli and S. typhimurium are induced by deoxynucleosides and have also been reported to respond with cytidine (Hammer-Jespersen et al, 1971).…”

Section: Discussionmentioning

confidence: 66%

Induction of nucleoside phosphorylase in Enterobacter aerogenes and enzymatic synthesis of adenine arabinoside

Wei

Ding

Zhang

et al. 2008

J. Zhejiang Univ. Sci. B

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Nucleoside phosphorylases (NPases) were found to be induced in Enterobacter aerogenes DGO-04, and cytidine and cytidine 5′-monophosphate (CMP) were the best inducers. Five mmol/L to fifteen mmol/L cytidine or CMP could distinctly increase the activities of purine nucleoside phosphorylase (PNPase), uridine phosphorylase (UPase) and thymidine phosphorylase (TPase) when they were added into medium from 0 to 8 h. In the process of enzymatic synthesis of adenine arabinoside from adenine and uracil arabinoside with wet cells of Enterobacter aerogenes DGO-04 induced by cytidine or CMP, the reaction time could be shortened from 36 to 6 h. After enzymatic reaction the activity of NPase in the cells induced remained higher than that in the cells uninduced.

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On the Catabolism of Deoxyribonucleosides in Cells and Cell Extracts of Escherichia coli

Cited by 84 publications

References 31 publications

Inability of Escherichia coliB to Incorporate Added Deoxycytidine, Deoxyadenosine, and Deoxyguanosine into DNA

Inability of Escherichia coliB to Incorporate Added Deoxycytidine, Deoxyadenosine, and Deoxyguanosine into DNA

De novo synthesis of thymidylate via deoxycytidine in dcd (dCTP deaminase) mutants of Escherichia coli

Induction of nucleoside phosphorylase in Enterobacter aerogenes and enzymatic synthesis of adenine arabinoside

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