Two residues of a conserved aromatic ladder of the mitochondrial ADP/ATP carrier are crucial to nucleotide transport.
The mitochondrial ADP/ATP carrier is the paradigm of the mitochondrial carrier family (MCF), whose members are crucial for cross-talks between mitochondria, where cell energy is mainly produced, and the cytosol, where cell energy is mainly consumed. These carriers share structural and functional characteristics. Resolution of the 3D structure of the beef mitochondrial ADP/ATP carrier, in a complex with one of its specific inhibitors, revealed interesting features and suggested the involvement of some particular residues in substrate binding and transfer from the outside to the inside of mitochondria. To ascertain the role of these residues, namely, Y186, Y190, F191, and Y194, they were mutated into alanine in the yeast mitochondrial ADP/ATP carrier at equivalent positions (Y203, Y207, F208, and Y211). Two residues, Y203 and F208, appeared to be crucial for transport activity but not for substrate binding per se, indicating their involvement in the substrate transfer process through the carrier. Furthermore, it was possible to show that these mutations precluded conformational changes of the matrix loop m2, whose movements were demonstrated to participate in substrate transport by the wild-type carrier. Therefore, these aromatic residues may be involved in substrate gliding, and they may also confer specificity toward adenine nucleotides for the ADP/ATP carrier as compared with the MCF members.
David
Claudine
C
Laboratoire de Physiologie Moléculaire et Cellulaire, Institut de Biochimie et Génétique Cellulaires, UMR 5095, CNRS-Université Bordeaux 2, 1, rue Camille Saint-Saëns, F-33077 Bordeaux Cedex, France.
Arnou
Bertrand
B
Sanchez
Jean-Frédéric
JF
Pelosi
Ludovic
L
Brandolin
Gérard
G
Lauquin
Guy J M
GJ
Trézéguet
Véronique
V
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002417:Cattle; D017124:Conserved Sequence / Q000235:genetics; D018360:Crystallography, X-Ray; D000226:Mitochondrial ADP, ATP Translocases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*
D009711:Nucleotides; C112225:PET9 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000226:Mitochondrial ADP, ATP Translocases