The presequence pathway is involved in protein sorting to the mitochondrial outer membrane.
The mitochondrial outer membrane contains integral α-helical and β-barrel proteins that are imported from the cytosol. The machineries importing β-barrel proteins have been identified, however, different views exist on the import of α-helical proteins. It has been reported that the biogenesis of Om45, the most abundant signal-anchored protein, does not depend on proteinaceous components, but involves direct insertion into the outer membrane. We show that import of Om45 occurs via the translocase of the outer membrane and the presequence translocase of the inner membrane. Assembly of Om45 in the outer membrane involves the MIM machinery. Om45 thus follows a new mitochondrial biogenesis pathway that uses elements of the presequence import pathway to direct a protein to the outer membrane.
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany Faculty of Biology, Universität Freiburg, Freiburg, Germany.
Lena-Sophie
LS
Wenz
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany.
Lukasz
L
Opaliński
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany.
Max-Hinderk
MH
Schuler
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany Faculty of Biology, Universität Freiburg, Freiburg, Germany.
Lars
L
Ellenrieder
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany.
Raffaele
R
Ieva
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany Faculty of Biology, Universität Freiburg, Freiburg, Germany.
Lena
L
Böttinger
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany Spemann Graduate School of Biology and Medicine, Universität Freiburg, Freiburg, Germany.
Jian
J
Qiu
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany.
Martin
M
van der Laan
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany.
Nils
N
Wiedemann
Centre de Génétique Moléculaire, CNRS, Gif-sur-Yvette, France.
Bernard
B
Guiard
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany nikolaus.pfanner@biochemie.uni-freiburg.de.
Nikolaus
N
Pfanner
Institut für Biochemie und Molekularbiologie, ZBMZ Universität Freiburg, Freiburg, Germany BIOSS Centre for Biological Signalling Studies, Universität Freiburg, Freiburg, Germany.
Thomas
T
Becker
D001345:Autoradiography; D002352:Carrier Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000502:physiology*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D016296:Mutagenesis; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D021381:Protein Transport / Q000502:physiology*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*
D002352:Carrier Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; C000594449:Om45 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C083081:TIM23 protein, S cerevisiae
Saccharomyces cerevisiae; intermembrane space; mitochondria; outer membrane; protein sorting