Deoxyribonucleotide Synthesis & Ribonucleotide ..

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Deoxyribonucleotides and Deoxythymidylate Synthesis - …

T1 - A novel regulatory mechanism couples deoxyribonucleotide synthesis and DNA replication in Escherichia coli

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Keyword - Deoxyribonucleotide synthesis (KW-0215)

Prerequisites: Basic Biochemistry (SBS017). This module covers a range of topics including: Chemical reactions - Biochemical logic. Biochemistry of some vitamin and coenzyme catalysed reactions. Glycogen synthesis and degradation. Pentose phosphate pathway. Gluconeogenesis. Amino acid metabolism and the urea cycle. Fatty acid synthesis and breakdown. Prostaglandin and steroid biosynthesis. Purine, pyrimidine and deoxyribonucleotide synthesis. Control and regulation of metabolism.

30/11/2013 · Deoxyribonucleotide biosynthesis - Duration: 7:56

AB - We present evidence for a complex regulatory interplay between the initiation of DNA replication and deoxyribonucleotide synthesis. In Escherichia coli, the ATP-bound DnaA protein initiates chromosomal replication. Upon loading of the β-clamp subunit (DnaN) of the replicase, DnaA is inactivated as its intrinsic ATPase activity is stimulated by the protein Hda. The β-subunit acts as a matchmaker between Hda and DnaA. Chain elongation of DNA requires a sufficient supply of deoxyribonucleotides (dNTPs), which are produced by ribonucleotide reductase (RNR). We present evidence suggesting that the molecular switch from ATP-DnaA to ADP-DnaA is a critical step coordinating DNA replication with increased deoxyribonucleotide synthesis. Characterization of dnaA and dnaN mutations that result in a constitutively high expression of RNR reveal this mechanism. We propose that the nucleotide bound state of DnaA regulates the transcription of the genes encoding ribonucleotide reductase (nrdAB). Accordingly, the conversion of ATP-DnaA to ADP-DnaA after initiation and loading of the β-subunit DnaN would allow increased nrdAB expression, and consequently, coordinated RNR synthesis and DNA replication during the cell cycle.

Control of deoxyribonucleotide synthesis in vitro and …

Protein involved in the synthesis of deoxyribonucleotides, the basic repeating units in DNA

For salvage of deoxyribonucleoside monophosphates released by intracellular DNA degradation, the deoxyribonucleoside monophosphate kinases play the key roles. Animal cells contain four such enzymes, each specific for one deoxyribonucleotide, ie, dAMP kinase, dCMP kinase, dGMP kinase, and dTMP kinase . The enzyme phosphorylating dAMP acts also on AMP and is the well-known adenylate kinase, or myokinase. dCMP kinase acts also on UMP, and dTMP kinase acts also on dUMP. dTMP kinase is involved also in de novo dTTP synthesis, as shown in Figure 1. dCMP kinase may also play a role in de novo dNTP synthesis. The enzyme converting dCDP (produced by ribonucleotide reductase) to dCMP, en route to dUMP and dTMP, has still not been identified. Since nucleotide kinases all have equilibrium constants close to 1, it is quite possible that the role of dCMP kinase is to carry out the synthesis of dCMP:

As noted in Salvage pathways to nucleotide biosynthesis, deoxyribonucleotide salvage pathways involving uptake of extracellular precursors primarily use deoxyribonucleoside kinases. Human cells contain four such enzymes of varying specificities, two located in the cytosol and two in mitochondria, whereas other organisms, such as E. coli, contain thymidine kinase as the only deoxyribonucleoside kinase. Thymidine kinase has received particularly intensive study, partly because of the mechanism of its cell cycle regulation (9) but largely because the enzyme is so useful as a means for incorporating radiolabel into DNA. For reasons still not clear, thymidine competes extremely effectively with the de novo synthetic pathway to dTTP such that, in many animal cell systems, radiolabeled thymidine is incorporated into DNA at full specific activity, often bypassing substantial endogenous pools generated by de novo synthesis (10). One popular experimental organism for which this does not work is yeast; fungi lack thymidine kinase. Investigators have circumvented this difficulty, however, by designing yeast strains that are permeable to dTMP, strains for which exogenous dTMP can be used as a labeled DNA precursor.

Pathways of pyrimidine deoxyribonucleotide biosynthesis …

Pathways of pyrimidine deoxyribonucleotide biosynthesis in Mycoplasma mycoides ..

. Now the deoxyribose-1-phosphate can react with another base in anucleoside phosphorylase-catalyzed reaction proceeding in the reverse direction, eg,Thymidine can then become a nucleotide via the thymidine kinase reaction leading to dTMP. Although this process can significantly change relative dNTP pool sizes, it does not involve net deoxyribonucleotide synthesis; rather, it involves redistribution of the deoxyribosyl units linked to purine and pyrimidine bases.

While this interaction is essential for the de novo synthesis of deoxyribonucleotides, it is unclear whether this association is necessary for other biological activities ascribed to RRM1.

Deoxyribonucleotide synthesis Flashcards | Quizlet
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    Deoxyribonucleotide synthesis essay - AJFMAQUINARIA

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A ribo-deoxyribonucleotide primer synthesized by primase.

We present evidence for a complex regulatory interplay between the initiation of DNA replication and deoxyribonucleotide synthesis. In Escherichia coli, the ATP-bound DnaA protein initiates chromosomal replication. Upon loading of the β-clamp subunit (DnaN) of the replicase, DnaA is inactivated as its intrinsic ATPase activity is stimulated by the protein Hda. The β-subunit acts as a matchmaker between Hda and DnaA. Chain elongation of DNA requires a sufficient supply of deoxyribonucleotides (dNTPs), which are produced by ribonucleotide reductase (RNR). We present evidence suggesting that the molecular switch from ATP-DnaA to ADP-DnaA is a critical step coordinating DNA replication with increased deoxyribonucleotide synthesis. Characterization of dnaA and dnaN mutations that result in a constitutively high expression of RNR reveal this mechanism. We propose that the nucleotide bound state of DnaA regulates the transcription of the genes encoding ribonucleotide reductase (nrdAB). Accordingly, the conversion of ATP-DnaA to ADP-DnaA after initiation and loading of the β-subunit DnaN would allow increased nrdAB expression, and consequently, coordinated RNR synthesis and DNA replication during the cell cycle.

deoxyribonucleotide biosynthetic process Antibodies

With the exception of the discussions of purine and pyrimidine nucleotidedegradation, which are generalized to ribonucleotides and deoxyribonucleotides,the biosynthetic pathways that we have looked at were specific toribonucleotides and, therefore, to RNA. Now we want to build upon this todiscuss the components of DNA, the deoxyribonucleotides.

Deoxyribonucleotide - Wikipedia

N2 - We present evidence for a complex regulatory interplay between the initiation of DNA replication and deoxyribonucleotide synthesis. In Escherichia coli, the ATP-bound DnaA protein initiates chromosomal replication. Upon loading of the β-clamp subunit (DnaN) of the replicase, DnaA is inactivated as its intrinsic ATPase activity is stimulated by the protein Hda. The β-subunit acts as a matchmaker between Hda and DnaA. Chain elongation of DNA requires a sufficient supply of deoxyribonucleotides (dNTPs), which are produced by ribonucleotide reductase (RNR). We present evidence suggesting that the molecular switch from ATP-DnaA to ADP-DnaA is a critical step coordinating DNA replication with increased deoxyribonucleotide synthesis. Characterization of dnaA and dnaN mutations that result in a constitutively high expression of RNR reveal this mechanism. We propose that the nucleotide bound state of DnaA regulates the transcription of the genes encoding ribonucleotide reductase (nrdAB). Accordingly, the conversion of ATP-DnaA to ADP-DnaA after initiation and loading of the β-subunit DnaN would allow increased nrdAB expression, and consequently, coordinated RNR synthesis and DNA replication during the cell cycle.

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