Send to

Choose Destination
Proc Natl Acad Sci U S A. 2009 Feb 24;106(8):2531-6. doi: 10.1073/pnas.0807830106. Epub 2009 Jan 30.

Signals in bacterial beta-barrel proteins are functional in eukaryotic cells for targeting to and assembly in mitochondria.

Author information

Interfaculty Institute for Biochemistry, University of Tübingen, 72076 Tübingen, Germany.


The outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts harbor beta-barrel proteins. The signals that allow precursors of such proteins to be targeted to mitochondria were not characterized so far. To better understand the mechanism by which beta-barrel precursor proteins are recognized and sorted within eukaryotic cells, we expressed the bacterial beta-barrel proteins PhoE, OmpA, Omp85, and OmpC in Saccharomyces cerevisiae and demonstrated that they were imported into mitochondria. A detailed investigation of the import pathway of PhoE revealed that it is shared with mitochondrial beta-barrel proteins. PhoE interacts initially with surface import receptors, and its further sorting depends on components of the TOB/SAM complex. The bacterial Omp85 and PhoE integrated into the mitochondrial outer membrane as native-like oligomers. For the latter protein this assembly depended on the C-terminal Phe residue, which is important also for the correct assembly of PhoE into the bacterial outer membrane. Collectively, it appears that mitochondrial beta-barrel proteins have not evolved eukaryotic-specific signals to ensure their import into mitochondria. Furthermore, the signal for assembly of beta-barrel proteins into the bacterial outer membrane is functional in mitochondria.

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center