Switching of the homooligomeric ATP-binding cassette transport complex MDL1 from post-translational mitochondrial import to endoplasmic reticulum insertion.
The ATP-binding cassette transporter MDL1 of Saccharomyces cerevisiae has been implicated in mitochondrial quality control, exporting degradation products of misassembled respiratory chain complexes. In the present study, we identified an unusually long leader sequence of 59 amino acids, which targets MDL1 to the inner mitochondrial membrane with its nucleotide-binding domain oriented to the matrix. By contrast, MDL1 lacking this leader sequence is directed into the endoplasmic reticulum membrane with the nucleotide-binding domain facing the cytosol. Remarkably, in both targeting routes, the ATP-binding cassette transporter maintains its intrinsic properties of membrane insertion and assembly, leading to homooligomeric complexes with similar activities in ATP hydrolysis. The physiological consequences of both targeting routes were elucidated in cells lacking the mitochondrial ATP-binding cassette transporter ATM1, which is essential for biogenesis of cytosolic iron-sulfur proteins. The mitochondrial MDL1 complex can complement ATM1 function, whereas the endoplasmic reticulum-targeted version, as well as MDL1 mutants deficient in ATP binding and hydrolysis, cannot overcome the Deltaatm1 growth phenotype.
Gompf
Simone
S
Institute of Biochemistry, Biocenter, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.
Zutz
Ariane
A
Hofacker
Matthias
M
Haase
Winfried
W
van der Does
Chris
C
Tampé
Robert
R
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D019281:Dimerization; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D015951:Factor Xa / Q000378:metabolism; D005816:Genetic Complementation Test; D006868:Hydrolysis; D008928:Mitochondria / Q000378:metabolism*; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
C091561:ATM1 protein, S cerevisiae; D018528:ATP-Binding Cassette Transporters; C490069:MDL1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; D015951:Factor Xa; D000251:Adenosine Triphosphatases