Identification of the yeast mitochondrial transporter for oxaloacetate and sulfate.
Saccharomyces cerevisiae encodes 35 members of the mitochondrial carrier family, including the OAC protein. The transport specificities of some family members are known, but most are not. The function of the OAC has been revealed by overproduction in Escherichia coli, reconstitution into liposomes, and demonstration that the proteoliposomes transport malonate, oxaloacetate, sulfate, and thiosulfate. Reconstituted OAC catalyzes both unidirectional transport and exchange of substrates. In S. cerevisiae, OAC is in inner mitochondrial membranes, and deletion of its gene greatly reduces transport of oxaloacetate sulfate, thiosulfate, and malonate. Mitochondria from wild-type cells swelled in isoosmotic solutions of ammonium salts of oxaloacetate, sulfate, thiosulfate, and malonate, indicating that these anions are cotransported with protons. Overexpression of OAC in the deletion strain increased greatly the [(35)S]sulfate/sulfate and [(35)S]sulfate/oxaloacetate exchanges in proteoliposomes reconstituted with digitonin extracts of mitochondria. The main physiological role of OAC appears to be to use the proton-motive force to take up into mitochondria oxaloacetate produced from pyruvate by cytoplasmic pyruvate carboxylase.
Palmieri
L
L
Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Via Orabona 4, 70125 Bari, Italy.
Vozza
A
A
Agrimi
G
G
De Marco
V
V
Runswick
M J
MJ
Palmieri
F
F
Walker
J E
JE
D027321:Anion Transport Proteins; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008314:Malonates / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D062907:Oxaloacetic Acid / Q000378:metabolism*; D011510:Proteolipids; D018892:Proton-Motive Force; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D013431:Sulfates / Q000378:metabolism*; D013885:Thiosulfates / Q000378:metabolism
D027321:Anion Transport Proteins; D002352:Carrier Proteins; D005656:Fungal Proteins; D008314:Malonates; C120763:OAC protein, S cerevisiae; D011510:Proteolipids; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D013431:Sulfates; D013885:Thiosulfates; C020485:proteoliposomes; D062907:Oxaloacetic Acid; C030290:malonic acid