A toxic fusion protein accumulating between the mitochondrial membranes inhibits protein assembly in vivo

Traude Beilharz, Carolyn K. Suzuki, Trevor Lithgow

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When overexpressed in Saccharomyces cerevisiae, β-galactosidase fusion proteins directed to the mitochondria are toxic, preventing growth of yeast cells on non-fermentable carbon sources (Emr, S. D., Vassarotti, A., Garrett, J., Geller, B. L., Takeda, M., and Douglas, M. G. (1986) J. Cell Biol. 102, 523-533). We show that such fusion proteins interfere with the assembly of respiratory complexes in the mitochondrial inner membrane, without blocking protein translocation. The gene YME1, encoding an ATP-dependent metalloprotease of the mitochondrial inner membrane, acts as a suppressor of this defect; a 3-fold overexpression of Yme1p is sufficient to restore respiratory complex assembly and mitochondrial function. Detailed knowledge of the topology and effect of the toxic β-galactosidase fusion proteins will permit the identification and characterization of components that control protein sorting and protein assembly within the mitochondrial inner membrane.

Original languageEnglish
Pages (from-to)35268-35272
Number of pages5
JournalJournal of Biological Chemistry
Issue number52
Publication statusPublished - 25 Dec 1998
Externally publishedYes

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