Publication

Membrane integration of a mitochondrial signal-anchored protein does not require additional proteinaceous factors

Merklinger, E., Gofman, Y., Kedrov, A., Driessen, A. J. M., Ben-Tal, N., Shai, Y. & Rapaport, D., 1-Mar-2012, In : Biochemical Journal. 442, 2, p. 381-389 9 p.

Research output: Contribution to journalArticleAcademicpeer-review

The MOM (mitochondrial outer membrane) contains SA (signal-anchored) proteins that bear at their N-terminus a single hydrophobic segment that serves as both a mitochondria] targeting signal and an anchor at the membrane. These proteins, like the vast majority of mitochondrial proteins, are encoded in the nucleus and have to be imported into the organelle. Currently, the mechanisms by which they are targeted to and inserted into the OM (outer membrane) are unclear. To shed light on these issues, we employed a recombinant version of the SA protein OM45 and a synthetic peptide corresponding to its signal-anchor segment. Both forms are associated with isolated mitochondria independently of cytosolic factors. Interaction with mitochondria was diminished when a mutated form of the signal-anchor was employed. We demonstrate that the signal-anchor peptide acquires an a-helical structure in a lipid environment and adopted a TM (transmembrane) topology within artificial lipid bilayers. Moreover, the peptide's affinity to artificial membranes with OM-like lipid composition was much higher than that of membranes with ER (endoplasmic reticulum)-like lipid composition. Collectively, our results suggest that SA proteins are specifically inserted into the MOM by a process that is not dependent on additional proteins, but is rather facilitated by the distinct lipid composition of this membrane.

Original languageEnglish
Pages (from-to)381-389
Number of pages9
JournalBiochemical Journal
Volume442
Issue number2
Publication statusPublished - 1-Mar-2012

    Keywords

  • ergosterol, mitochondrion, outer membrane, signal-anchored protein (SA protein), OUTER-MEMBRANE, PHOSPHOLIPID-BILAYERS, SACCHAROMYCES-CEREVISIAE, ANTIMICROBIAL PEPTIDES, SUBCELLULAR MEMBRANES, INSERTION PATHWAY, LIPID-COMPOSITION, TOM COMPLEX, IMPORT, HELIX

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