A novel import route for an N-anchor mitochondrial outer membrane protein aided by the TIM23 complex.
The membrane topology of Om45 in the yeast mitochondrial outer membrane (OM) is under debate. Here, we confirm that Om45 is anchored to the OM from the intermembrane space (IMS) by its N-terminal hydrophobic segment. We show that import of Om45 requires the presequence receptors, Tom20 and Tom22, and the import channel of Tom40. Unlike any of the known OM proteins, Om45 import requires the TIM23 complex in the inner membrane, a translocator for presequence-containing proteins, and the membrane potential (ΔΨ). Therefore, Om45 is anchored to the OM via the IMS by a novel import pathway involving the TIM23 complex.
Department of Chemistry, Graduate School of Science Nagoya University, Chikusa-ku Nagoya, Japan.
Jiyao
J
Song
Research Center for Materials Science Nagoya University, Chikusa-ku Nagoya, Japan.
Yasushi
Y
Tamura
Graduate School of Life Science University of Hyogo, Hyogo, Japan.
Tohru
T
Yoshihisa
Department of Chemistry, Graduate School of Science Nagoya University, Chikusa-ku Nagoya, Japan Structural Biology Research Center Nagoya University, Chikusa-ku Nagoya, Japan JST CREST Nagoya University, Chikusa-ku Nagoya, Japan endo@chem.nagoya-u.ac.jp.
Toshiya
T
Endo
D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D057927:Hydrophobic and Hydrophilic Interactions; D015151:Immunoblotting; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008958:Models, Molecular; D017830:Octoxynol; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
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; C489350:TOM20 protein, S cerevisiae; C090857:TOM22 protein, S cerevisiae; C066555:Tom40 protein, S cerevisiae; D017830:Octoxynol
Om45; mitochondria; translocator; yeast