The ATP-dependent PIM1 protease is required for the expression of intron-containing genes in mitochondria
Abstract
The ATP-dependent PIM1 protease, a Lon-like protease localized in the mitochondrial matrix, is required for mitochondrial genome integrity in yeast. Cells lacking PIM1 accumulate lesions in the mitochondrial DNA (mtDNA) and therefore lose respiratory competence. The identification of a multicopy suppressor, which stabilizes mtDNA in the absence of PIM1, enabled us to characterize novel functions of PIM1 protease during mitochondrial biogenesis. The synthesis of mitochondrially encoded cytochrome c oxidase subunit I (CoxI) and cytochrome b (Cob) is impaired in pim1 mutants containing mtDNA. PIM1-mediated proteolysis is required for the translation of mature COXI mRNA. Moreover, deficiencies in the splicing of COXI and COB transcripts, which appear to be restricted to introns encoding mRNA maturases, were observed in cells lacking the PIM1 gene. Transcripts of COXI andCOB genes harboring multiple introns are degraded in the absence of PIM1. These results establish multiple, essential functions of the ATP-dependent PIM1 protease during mitochondrial gene expression.
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Footnotes
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↵1 Corresponding author.
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E-MAIL: Langer{at}bio.med.uni-muenchen.de; FAX 49 89 5996 270.
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- Received November 25, 1997.
- Accepted March 11, 1998.
- Cold Spring Harbor Laboratory Press
