The human mitochondrial deoxynucleotide carrier and its role in the toxicity of nucleoside antivirals.
The synthesis of DNA in mitochondria requires the uptake of deoxynucleotides into the matrix of the organelle. We have characterized a human cDNA encoding a member of the family of mitochondrial carriers. The protein has been overexpressed in bacteria and reconstituted into phospholipid vesicles where it catalyzed the transport of all four deoxy (d) NDPs, and, less efficiently, the corresponding dNTPs, in exchange for dNDPs, ADP, or ATP. It did not transport dNMPs, NMPs, deoxynucleosides, nucleosides, purines, or pyrimidines. The physiological role of this deoxynucleotide carrier is probably to supply deoxynucleotides to the mitochondrial matrix for conversion to triphosphates and incorporation into mitochondrial DNA. The protein is expressed in all human tissues that were examined except for placenta, in accord with such a central role. The deoxynucleotide carrier also transports dideoxynucleotides efficiently. It is likely to be medically important by providing the means of uptake into mitochondria of nucleoside analogs, leading to the mitochondrial impairment that underlies the toxic side effects of such drugs in the treatment of viral illnesses, including AIDS, and in cancer therapy.
Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Via E. Orabona 4, 70125 Bari, Italy.
V
V
Dolce
G
G
Fiermonte
M J
MJ
Runswick
F
F
Palmieri
J E
JE
Walker
D000595:Amino Acid Sequence; D000998:Antiviral Agents / Q000633:toxicity*; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018076:DNA, Complementary; D006801:Humans; D026901:Membrane Transport Proteins; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015215:Zidovudine / Q000633:toxicity*
D000998:Antiviral Agents; D002352:Carrier Proteins; D018076:DNA, Complementary; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D011994:Recombinant Proteins; C434255:SLC25A19 protein, human; D015215:Zidovudine