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A novel import route for an N-anchor mitochondrial outer membrane protein aided by the TIM23 complex

Jiyao Song1, Yasushi Tamura2, Tohru Yoshihisa3

  • 1Department of Chemistry, Graduate School of Science Nagoya University, Chikusa-ku Nagoya, Japan.

EMBO Reports
|May 1, 2014
PubMed

Insights

Om45 anchors to the yeast mitochondrial outer membrane (OM) from the intermembrane space (IMS). This novel OM protein import pathway utilizes the TIM23 complex and membrane potential (ΔΨ).

Area of Science:

  • Mitochondrial biology
  • Protein import
  • Cellular membrane topology

Background:

  • The precise membrane topology of Om45 in the yeast mitochondrial outer membrane (OM) remains a subject of scientific discussion.
  • Understanding the mechanisms of outer membrane protein insertion is crucial for mitochondrial function.

Purpose of the Study:

  • To elucidate the membrane topology and import pathway of the Om45 protein in yeast mitochondria.
  • To identify the specific protein complexes and membrane potentials involved in Om45 translocation.

Main Methods:

  • Utilized yeast as a model organism.
  • Investigated protein import pathways using genetic and biochemical approaches.
  • Confirmed protein anchoring and localization within mitochondrial membranes.

Main Results:

  • Om45 is confirmed to be anchored to the OM from the intermembrane space (IMS) via its N-terminal hydrophobic segment.
  • Om45 import necessitates the presequence receptors Tom20 and Tom22, and the Tom40 import channel.
  • Uniquely, Om45 import requires the inner membrane TIM23 complex and the membrane potential (ΔΨ).

Conclusions:

  • Om45 is anchored to the mitochondrial outer membrane from the intermembrane space.
  • A novel protein import pathway involving the TIM23 complex facilitates Om45 translocation across the outer membrane.
  • This pathway highlights a previously unrecognized mechanism for outer membrane protein insertion in yeast mitochondria.
Keywords:
Om45mitochondriatranslocatoryeast

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