title: Role of phosphatidylethanolamine in the biogenesis of mitochondrial outer membrane proteins.
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.
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, 79104 Freiburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Becker
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, 79104 Freiburg, Germany; Institut für Biochemie, Technische Universität Graz, A-8010 Graz, Austria.
authors.forename: Susanne E
authors.initials: SE
authors.lastname: Horvath
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, 79104 Freiburg, Germany; Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Böttinger
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, 79104 Freiburg, Germany.
authors.forename: Natalia
authors.initials: N
authors.lastname: Gebert
authors.affiliation: Institut für Biochemie, Technische Universität Graz, A-8010 Graz, Austria. Electronic address: guenther.daum@tugraz.at.
authors.forename: Günther
authors.initials: G
authors.lastname: Daum
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, 79104 Freiburg, Germany. Electronic address: nikolaus.pfanner@biochemie.uni-freiburg.de.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Pfanner
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D010714:Phosphatidylethanolamines; D029701:Saccharomyces cerevisiae Proteins; C483858:phosphatidylethanolamine
keywords: Membrane Biogenesis; Mitochondria; Phospholipid; Protein Targeting; Protein Translocation