High impact information on NT5M

• We suggest that dNT-2 protects mitochondrial DNA replication from overproduction of dTTP, in particular in resting cells [1].
• The two enzymes share many catalytic properties, but dNT-2 shows a narrower substrate specificity [1].
• We localized the gene for dNT-2 on chromosome 17p11.2 in the Smith-Magenis syndrome-critical region, raising the possibility that dNT-2 is involved in the etiology of this genetic disease [1].
• The enzyme, named dNT-2, dephosphorylates specifically the 5'- and 2'(3')-phosphates of uracil and thymine deoxyribonucleotides [1].
• We modify the in situ activity of mdN and measure the transfer of radioactivity from [(3)H]thymidine to mt thymidine phosphates [2].

Biological context of NT5M

• These results suggest that mdN modulates the synthesis of mt dTTP by counteracting in a substrate cycle the phosphorylation of thymidine by the mt thymidine kinase [2].
• In cycling cells lacking the cytosolic thymidine kinase, a 30-fold overproduction of mdN decreases the specific radioactivity of mt dTTP to 25%, and an 80% decrease of mdN by RNA interference increases the specific radioactivity 2-fold [2].

Anatomical context of NT5M

• We now establish that dNT2 in vivo indeed is located in mitochondria [3].
• We constructed ponasterone-inducible cell lines overproducing dNT2 with and without the green fluorescent protein (GFP) linked to its C terminus [3].

Associations of NT5M with chemical compounds

• Overproduction of dNT2 did not lead to an increased excretion of pyrimidine deoxyribonucleosides, in contrast to overproduction of the corresponding cytosolic deoxynucleotidase, suggesting that the mitochondrial enzyme does not affect overall cellular deoxynucleotide turnover [3].
• We earlier obtained evidence for a mitochondrial 5'-nucleotidase (dNT2) with a pronounced specificity for dUMP and dTMP and suggested that the enzyme protects mitochondrial DNA replication from excess dTTP [3].
• Of the tested analogs, only (E)-5-(2-bromovinyl)-2'-deoxyuridine was preferentially dephosphorylated by mitochondrial dNT-2 [4].

Other interactions of NT5M

• When we analyzed additional genes involved in the dNTPs pool, such as SLC25A19 (DNC) and NT5M (d-NT2), we did not detect mutations [5].
• We investigated the dephosphorylation of the 5'-phosphates of commonly used nucleoside analogs by two cytosolic (cN-II and dNT-1) and one mitochondrial (dNT-2) nucleotidase [4].

References