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Localization of mRNAs encoding human mitochondrial oxidative phosphorylation proteins

Shinya Matsumoto1, Takeshi Uchiumi, Toshiro Saito

  • 1Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.

Mitochondrion
|March 13, 2012
PubMed

Insights

Nuclear-encoded mitochondrial oxidative phosphorylation (OXPHOS) mRNAs encoding hydrophobic proteins localize near mitochondria. The Y-box binding protein-1 binds these OXPHOS mRNAs, impacting mitochondrial protein import.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Mitochondrial oxidative phosphorylation (OXPHOS) relies on proteins encoded by both nuclear and mitochondrial DNA.
  • Nuclear-encoded OXPHOS mRNAs exhibit specific subcellular localizations, but their proximity to mitochondria is not well understood.

Purpose of the Study:

  • To investigate the subcellular localization of nuclear-encoded OXPHOS mRNAs relative to mitochondria.
  • To identify factors involved in the mitochondrial targeting of these mRNAs.

Main Methods:

  • Comparison of mRNA populations in mitochondria-bound polysome fractions versus free cytosolic polysome fractions.
  • Analysis of transmembrane domains in OXPHOS proteins.
  • Investigation of the RNA-binding protein Y-box binding protein-1 (YBX1) localization and binding to OXPHOS mRNAs.

Main Results:

  • mRNAs encoding hydrophobic OXPHOS proteins, destined for the inner mitochondrial membrane, were found localized near mitochondria.
  • OXPHOS mRNAs with fewer than one transmembrane domain were predominantly localized in the cytosol.
  • Y-box binding protein-1 was identified at the mitochondrial outer membrane, bound to OXPHOS mRNAs.

Conclusions:

  • Specific OXPHOS mRNAs are targeted to mitochondrial vicinity for co-translational import.
  • Hydrophobicity and transmembrane domain count correlate with mRNA localization.
  • Y-box binding protein-1 plays a role in the mitochondrial association of OXPHOS mRNAs.

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