5-Bromovinyl 2′-Deoxyuridine Phosphorylation by Mitochondrial and Cytosolic Thymidine Kinase (TK2 and TK1) and Its Use in Selective Measurement of TK2 Activity in Crude Extracts

@article{Wang20085Bromovinyl2P,
  title={5-Bromovinyl 2′-Deoxyuridine Phosphorylation by Mitochondrial and Cytosolic Thymidine Kinase (TK2 and TK1) and Its Use in Selective Measurement of TK2 Activity in Crude Extracts},
  author={Liya Wang and Staffan K Eriksson},
  journal={Nucleosides, Nucleotides \& Nucleic Acids},
  year={2008},
  volume={27},
  pages={858 - 862}
}
  • Liya Wang, S. Eriksson
  • Published 3 July 2008
  • Biology, Chemistry
  • Nucleosides, Nucleotides & Nucleic Acids
Mitochondrial thymidine kinase (TK2) is responsible for phosphorylation of thymidine and deoxycytidine and plays a crucial role in mitochondrial DNA precursor synthesis. TK2 is expressed in all tissues at low levels complicating accurate determinations, especially in tissues with high cytosolic thymidine kinase (TK1) activity. Recently, 5-bromovinyl 2 ′-deoxyuridine (BvdU) at 0.2 μ M was used to measure TK2 activity selectively. BvdU phosphorylation by pure human TK2 and TK1 was tested here… 

Thymidine kinase 2 enzyme kinetics elucidate the mechanism of thymidine-induced mitochondrial DNA depletion.

TLDR
Stochastic studies of the enzyme kinetic behavior of TK2 enzyme variants are used to explain the mechanism of mtDNA depletion caused by TK1 mutations, thymidine overload due toThymidine phosphorylase deficiency, and mitochondrial toxicity caused by antiviral Thymidine nucleoside analogues.

Basic biochemical characterization of cytosolic enzymes in thymidine nucleotide synthesis in adult rat tissues: implications for tissue specific mitochondrial DNA depletion and deoxynucleoside-based therapy for TK2-deficiency

TLDR
It is strongly indicated that mitochondria in most tissues are capable of producing enough dTTP for mtDNA replication via mitochondrial TK2, but skeletal muscle mitochondria do not and are most likely dependent on both the salvage and de novo synthesis pathways.

Studies of enzymes in mitochondrial DNA precursor synthesis

TLDR
The potential mechanism underlying pyrimidine nucleoside analogs-associated mitochondrial toxicities was investigated, and it was found that thymidine analogs had opposite effects on dThd and dCyd phosphorylation and thus can inhibit dThD salvage, leading to imbalanced dTTP and dCTP pools.

The role of 5'-nucleotidases and Deoxynucleoside Kinases in Responses to Nucleoside Analogues

TLDR
The aims of the present thesis were to elucidate mechanism(s) involved in tissue-specific toxicity associated with NA therapy, as well as the mechanisms underlying resistance to these drugs.

Transgene Expression of Drosophila melanogaster Nucleoside Kinase Reverses Mitochondrial Thymidine Kinase 2 Deficiency*♦

TLDR
The Dm-dNK+/−TK2−/− mouse model illustrates how dT MP synthesized in the cell nucleus can compensate for loss of intramitochondrial dTMP synthesis in differentiated tissue.

Onset and organ specificity of Tk2 deficiency depends on Tk1 down-regulation and transcriptional compensation.

TLDR
It is revealed that Tk2-/- heart significantly increases mitochondrial transcript levels relative to the mtDNA content and down-regulating the expression of the mitochondrial transcriptional terminator transcription factor 3 (MTERF3) allows the heart to maintain normal levels of mtDNA-encoded proteins.

Purine and Pyrimidine Metabolism

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Expression of deoxynucleoside kinases and 5'-nucleotidases in mouse tissues: implications for mitochondrial toxicity.

Substrate Specificities of Mitochondrial Thymidine Kinase and Cytosolic Deoxycytidine Kinase Against 5-Aryl Substituted Pyrimidine-2′-deoxyribose Analogues

TLDR
5-aryl-2′-deoxyuridine and -deoxycytidine analogues, many with known antiviral activity, were evaluated as substrates for pure dCK and pure mitochondrial thymidine kinase and TK2 showed the highest activity with this type of analogues.