Mitochondrial bovine ADP/ATP carrier in detergent is predominantly monomeric but also forms multimeric species.
ADP/ATP carriers (AACs) are major and essential constituents of the inner mitochondrial membrane. They drive the import of ADP and the export of newly synthesized ATP. They were described as functional dimers from the 1980s until the structures of the AAC shed doubt on this consensus. We aimed to ascertain the published biophysical data claiming that AACs are dimers and to characterize the oligomeric state of the protein before crystallization. Analytical ultracentrifugation sedimentation velocity experiments clearly show that the bovine AAC is a monomer in 3-laurylamido-N,N'-dimethylpropylaminoxide (LAPAO), whereas in Triton X-100 and reduced Triton X-100, higher molecular mass species can also be identified. Neutron scattering data for monomeric bovine AAC in LAPAO does not give definite conclusions on the association state, because the large amount of detergent and lipids is imperfectly matched by contrast methods. We discuss a possible way to integrate previously published biochemical evidence in favor of assemblies, the lack of well-defined multimers that we observe, and the information from the high-resolution structures, considering supramolecular organizations of AACs within the mitochondrial membrane.
Nury
Hugues
H
CEA, DSV, and CNRS and Universite Joseph Fourier, Institut de Biologie Structurale, 41 rue Jules Horowitz, F-38027, Grenoble, France.
Manon
Florence
F
Arnou
Bertrand
B
le Maire
Marc
M
Pebay-Peyroula
Eva
E
Ebel
Christine
C
D000818:Animals; D002417:Cattle; D045424:Complex Mixtures / Q000494:pharmacology; D003460:Crystallization; D003902:Detergents / Q000494:pharmacology*; D008055:Lipids / Q000494:pharmacology; D008823:Micelles; D000226:Mitochondrial ADP, ATP Translocases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000378:metabolism; D033363:Neutron Diffraction; D017830:Octoxynol / Q000494:pharmacology; D020033:Protein Isoforms / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D055503:Protein Multimerization / Q000187:drug effects*; D020836:Protein Structure, Quaternary / Q000187:drug effects; D053838:Scattering, Small Angle; D012995:Solubility; D014461:Ultracentrifugation
D045424:Complex Mixtures; D003902:Detergents; D008055:Lipids; D008823:Micelles; D020033:Protein Isoforms; C054295:aminoxide WS 35; D017830:Octoxynol; D000226:Mitochondrial ADP, ATP Translocases