Publications

• Identification of the mitochondrial NAD+ transporter in Saccharomyces cerevisiae.

  Todisco S., Agrimi G., Castegna A., Palmieri F.

  The mitochondrial carriers are a family of transport proteins that shuttle metabolites, nucleotides, and cofactors across the inner mitochondrial membrane. In Saccharomyces cerevisiae, NAD+ is synthesized outside the mitochondria and must be imported across the permeability barrier of the inner mi ... >> More

  The mitochondrial carriers are a family of transport proteins that shuttle metabolites, nucleotides, and cofactors across the inner mitochondrial membrane. In Saccharomyces cerevisiae, NAD+ is synthesized outside the mitochondria and must be imported across the permeability barrier of the inner mitochondrial membrane. However, no protein responsible for this transport activity has ever been isolated or identified. In this report, the identification and functional characterization of the mitochondrial NAD+ carrier protein (Ndt1p) is described. The NDT1 gene was overexpressed in bacteria. The purified protein was reconstituted into liposomes, and its transport properties and kinetic parameters were characterized. It transported NAD+ and, to a lesser extent, (d)AMP and (d)GMP but virtually not alpha-NAD+, NADH, NADP+, or NADPH. Transport was saturable with an apparent Km of 0.38 mM for NAD+. The Ndt1p-GFP was found to be targeted to mitochondria. Consistently with Ndt1p localization and its function as a NAD+ transporter, cells lacking NDT1 had reduced levels of NAD+ and NADH in their mitochondria and reduced activity of mitochondrial NAD+-requiring enzymes. Similar results were also found in the mitochondria of cells lacking NDT2 that encodes a protein (Ndt2p) displaying 70% homology with Ndt1p. The delta ndt1 delta ndt2 double mutant exhibited lower mitochondrial NAD+ and NADH levels than the single deletants and a more pronounced delay in growth on nonfermentable carbon sources. The main role of Ndt1p and Ndt2p is to import NAD+ into mitochondria by unidirectional transport or by exchange with intramitochondrially generated (d)AMP and (d)GMP. << Less

  J. Biol. Chem. 281:1524-1531(2006) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• Molecular identification and functional characterization of Arabidopsis thaliana mitochondrial and chloroplastic NAD+ carrier proteins.

  Palmieri F., Rieder B., Ventrella A., Blanco E., Do P.T., Nunes-Nesi A., Trauth A.U., Fiermonte G., Tjaden J., Agrimi G., Kirchberger S., Paradies E., Fernie A.R., Neuhaus H.E.

  The Arabidopsis thaliana L. genome contains 58 membrane proteins belonging to the mitochondrial carrier family. Two mitochondrial carrier family members, here named AtNDT1 and AtNDT2, exhibit high structural similarities to the mitochondrial nicotinamide adenine dinucleotide (NAD(+)) carrier ScNDT ... >> More

  The Arabidopsis thaliana L. genome contains 58 membrane proteins belonging to the mitochondrial carrier family. Two mitochondrial carrier family members, here named AtNDT1 and AtNDT2, exhibit high structural similarities to the mitochondrial nicotinamide adenine dinucleotide (NAD(+)) carrier ScNDT1 from bakers' yeast. Expression of AtNDT1 or AtNDT2 restores mitochondrial NAD(+) transport activity in a yeast mutant lacking ScNDT. Localization studies with green fluorescent protein fusion proteins provided evidence that AtNDT1 resides in chloroplasts, whereas only AtNDT2 locates to mitochondria. Heterologous expression in Escherichia coli followed by purification, reconstitution in proteoliposomes, and uptake experiments revealed that both carriers exhibit a submillimolar affinity for NAD(+) and transport this compound in a counter-exchange mode. Among various substrates ADP and AMP are the most efficient counter-exchange substrates for NAD(+). Atndt1- and Atndt2-promoter-GUS plants demonstrate that both genes are strongly expressed in developing tissues and in particular in highly metabolically active cells. The presence of both carriers is discussed with respect to the subcellular localization of de novo NAD(+) biosynthesis in plants and with respect to both the NAD(+)-dependent metabolic pathways and the redox balance of chloroplasts and mitochondria. << Less

  J. Biol. Chem. 284:31249-31259(2009) [PubMed] [EuropePMC]

• SLC25A51 is a mammalian mitochondrial NAD+ transporter.

  Luongo T.S., Eller J.M., Lu M.J., Niere M., Raith F., Perry C., Bornstein M.R., Oliphint P., Wang L., McReynolds M.R., Migaud M.E., Rabinowitz J.D., Johnson F.B., Johnsson K., Ziegler M., Cambronne X.A., Baur J.A.

  Mitochondria require nicotinamide adenine dinucleotide (NAD⁺) to carry out the fundamental processes that fuel respiration and mediate cellular energy transduction. Mitochondrial NAD⁺ transporters have been identified in yeast and plants^1,2, but their existence in ... >> More

  Mitochondria require nicotinamide adenine dinucleotide (NAD⁺) to carry out the fundamental processes that fuel respiration and mediate cellular energy transduction. Mitochondrial NAD⁺ transporters have been identified in yeast and plants^1,2, but their existence in mammals remains controversial^3-5. Here we demonstrate that mammalian mitochondria can take up intact NAD⁺, and identify SLC25A51 (also known as MCART1)-an essential^6,7 mitochondrial protein of previously unknown function-as a mammalian mitochondrial NAD⁺ transporter. Loss of SLC25A51 decreases mitochondrial-but not whole-cell-NAD⁺ content, impairs mitochondrial respiration, and blocks the uptake of NAD⁺ into isolated mitochondria. Conversely, overexpression of SLC25A51 or SLC25A52 (a nearly identical paralogue of SLC25A51) increases mitochondrial NAD⁺ levels and restores NAD⁺ uptake into yeast mitochondria lacking endogenous NAD⁺ transporters. Together, these findings identify SLC25A51 as a mammalian transporter capable of importing NAD⁺ into mitochondria. << Less

  Nature 588:174-179(2020) [PubMed] [EuropePMC]