Role of Phosphatidylethanolamine in the Biogenesis of Mitochondrial Outer Membrane Proteins |
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| Authors: | Thomas Becker Susanne E Horvath Lena B?ttinger Natalia Gebert Günther Daum Nikolaus Pfanner |
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| Institution: | From the ‡Institut für Biochemie und Molekularbiologie, ZBMZ.;the §BIOSS Centre for Biological Signalling Studies, and ;the ‖Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany and ;the ¶Institut für Biochemie, Technische Universität Graz, A-8010 Graz, Austria |
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| Abstract: | The mitochondrial outer membrane contains proteinaceous machineries for the import and assembly of proteins, including TOM (translocase of the outer membrane) and SAM (sorting and assembly machinery). It has been shown that the dimeric phospholipid cardiolipin is required for the stability of TOM and SAM complexes and thus for the efficient import and assembly of β-barrel proteins and some α-helical proteins of the outer membrane. Here, we report that mitochondria deficient in phosphatidylethanolamine (PE), the second non-bilayer-forming phospholipid, are impaired in the biogenesis of β-barrel proteins, but not of α-helical outer membrane proteins. The stability of TOM and SAM complexes is not disturbed by the lack of PE. By dissecting the import steps of β-barrel proteins, we show that an early import stage involving translocation through the TOM complex is affected. In PE-depleted mitochondria, the TOM complex binds precursor proteins with reduced efficiency. We conclude that PE is required for the proper function of the TOM complex. |
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| Keywords: | Membrane Biogenesis Mitochondria Phospholipid Protein Targeting Protein Translocation |
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