Reconstituted TOM core complex and Tim9/Tim10 complex of mitochondria are sufficient for translocation of the ADP/ATP carrier across membranes

TY - JOUR

T1 - Reconstituted TOM core complex and Tim9/Tim10 complex of mitochondria are sufficient for translocation of the ADP/ATP carrier across membranes

AU - Vasiljev, Andreja

AU - Ahting, Uwe

AU - Nargang, Frank E

AU - Go, Nancy E

AU - Habib, Shukry J

AU - Kozany, Christian

AU - Panneels, Valérie

AU - Sinning, Irmgard

AU - Prokisch, Holger

AU - Neupert, Walter

AU - Nussberger, Stephan

AU - Rapaport, Doron

PY - 2004/3

Y1 - 2004/3

N2 - Precursor proteins of the solute carrier family and of channel forming Tim components are imported into mitochondria in two main steps. First, they are translocated through the TOM complex in the outer membrane, a process assisted by the Tim9/Tim10 complex. They are passed on to the TIM22 complex, which facilitates their insertion into the inner membrane. In the present study, we have analyzed the function of the Tim9/Tim10 complex in the translocation of substrates across the outer membrane of mitochondria. The purified TOM core complex was reconstituted into lipid vesicles in which purified Tim9/Tim10 complex was entrapped. The precursor of the ADP/ATP carrier (AAC) was found to be translocated across the membrane of such lipid vesicles. Thus, these components are sufficient for translocation of AAC precursor across the outer membrane. Peptide libraries covering various substrate proteins were used to identify segments that are bound by Tim9/Tim10 complex upon translocation through the TOM complex. The patterns of binding sites on the substrate proteins suggest a mechanism by which portions of membrane-spanning segments together with flanking hydrophilic segments are recognized and bound by the Tim9/Tim10 complex as they emerge from the TOM complex into the intermembrane space.

AB - Precursor proteins of the solute carrier family and of channel forming Tim components are imported into mitochondria in two main steps. First, they are translocated through the TOM complex in the outer membrane, a process assisted by the Tim9/Tim10 complex. They are passed on to the TIM22 complex, which facilitates their insertion into the inner membrane. In the present study, we have analyzed the function of the Tim9/Tim10 complex in the translocation of substrates across the outer membrane of mitochondria. The purified TOM core complex was reconstituted into lipid vesicles in which purified Tim9/Tim10 complex was entrapped. The precursor of the ADP/ATP carrier (AAC) was found to be translocated across the membrane of such lipid vesicles. Thus, these components are sufficient for translocation of AAC precursor across the outer membrane. Peptide libraries covering various substrate proteins were used to identify segments that are bound by Tim9/Tim10 complex upon translocation through the TOM complex. The patterns of binding sites on the substrate proteins suggest a mechanism by which portions of membrane-spanning segments together with flanking hydrophilic segments are recognized and bound by the Tim9/Tim10 complex as they emerge from the TOM complex into the intermembrane space.

KW - Amino Acid Sequence

KW - Binding Sites

KW - Carrier Proteins

KW - Cell Membrane

KW - Liposomes

KW - Membrane Proteins

KW - Membrane Transport Proteins

KW - Mitochondria

KW - Mitochondrial Membrane Transport Proteins

KW - Mitochondrial Proteins

KW - Molecular Sequence Data

KW - Neurospora crassa

KW - Peptides

KW - Saccharomyces cerevisiae

KW - Saccharomyces cerevisiae Proteins

KW - Sequence Homology

U2 - 10.1091/mbc.E03-05-0272

DO - 10.1091/mbc.E03-05-0272

M3 - Article

C2 - 14668492

SN - 1059-1524

VL - 15

SP - 1445

EP - 1458

JO - Mol Biol Cell

JF - Mol Biol Cell

IS - 3

ER -