TAILIEUCHUNG - Báo cáo khoa học: 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 ofSaccharomyces 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, | ễFEBS Journal Switching of the homooligomeric ATP-binding cassette transport complex MDL1 from post-translational mitochondrial import to endoplasmic reticulum insertion Simone Gompf1 Ariane Zutz1 Matthias Hofacker1 Winfried Haase2 Chris van der Does1 and Robert Tampe1 1 Institute of Biochemistry Biocenter Johann Wolfgang Goethe-University Frankfurt am Main Germany 2 Max-Planck Institute of Biophysics StructuralBiology Frankfurt am Main Germany Keywords ABC transporter ER targeting membrane protein trafficking transport ATPase mitochondrial import mitochondrial targeting sequence Correspondence R. Tampe Institute of Biochemistry Biocenter Johann Wolfgang Goethe-University Max-von-Laue-Strasse 9 D-60348 Frankfurt am Main Germany Fax 49 0 69 798 29495 Tel 49 0 69 798 29475 E-mail tampe@ Website http . Received 25 May 2007 revised 5 July 2007 accepted 20 August 2007 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 .

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