The role of protein degradation in mitochondrial function and biogenesis

Rep, Martijn; Grivell, Leslie A.

doi:10.1007/s002940050145

Cited by 103 publications

(60 citation statements)

References 177 publications

(138 reference statements)

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“…Thus, it would be expected that the mitochondrially encoded proteins that are synthesized in excess and not assembled into complexes would be degraded by specific protease activities, such as the one described by Sarria et al (1998). This does not seem to be happening to the same extent in the case of ATP1, COB, and NAD9 (i.e., their abundance does not decrease as much as the abundance of the nuclear-encoded subunits of the same complexes), but results from other experimental plant systems (Lu et al, 1996) and yeast (reviewed in Rep and Grivell, 1996) suggest that rapid degradation of nonfunctional or unassembled mitochondrially encoded proteins seems to be the norm in mitochondria.…”

Section: Discussionmentioning

confidence: 99%

Coordination of Nuclear and Mitochondrial Genome Expression during Mitochondrial Biogenesis in Arabidopsis

et al. 2005

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Mitochondrial biogenesis and function require the regulated and coordinated expression of nuclear and mitochondrial genomes throughout plant development and in response to cellular and environmental signals. To investigate the levels at which the expression of nuclear and mitochondrially encoded proteins is coordinated, we established an Arabidopsis thaliana cell culture system to modulate mitochondrial biogenesis in response to sugar starvation and refeeding. Sucrose deprivation led to structural changes in mitochondria, a decrease in mitochondrial volume, and a reduction in the rate of cellular respiration. All these changes could be reversed by the readdition of sucrose. Analysis of the relative mRNA transcript abundance of genes encoding nuclear and mitochondrially encoded proteins revealed that there was no coordination of expression of the two genomes at the transcript level. An analysis of changes in abundance and assembly of nuclear-encoded and mitochondrially encoded subunits of complexes I to V of the mitochondrial inner membrane in organello protein synthesis and competence for protein import by isolated mitochondria suggested that coordination occurs at the level of protein-complex assembly. These results further suggest that expression of the mitochondrial genome is insensitive to the stress imposed by sugar starvation and that mitochondrial biogenesis is regulated by changes in nuclear gene expression and coordinated at the posttranslational level.

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Section: Discussionmentioning

confidence: 99%

Coordination of Nuclear and Mitochondrial Genome Expression during Mitochondrial Biogenesis in Arabidopsis

et al. 2005

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“…It is known from many studies that subunits of mitochondrial inner membrane complexes in yeast are rapidly degraded when not assembled. (For a recent review on the role of protein degradation in mitochondrial function and biogenesis see [45].) The same occurs with some of the subcomplexes formed in the early stages of assembly of the bc, complex, including the cytochrome b subcomplex.…”

Section: Discussionmentioning

confidence: 99%

The Role of Subunit VIII in the Structural Stability of the bc₁ Complex from Saccharomyces cerevisiae Studied Using Hybrid Complexes

Boumans

Berden

Grivell

1997

European Journal of Biochemistry

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The QCR8 genes encoding subunit VIII of the bc, complex from Kluyveromyces lactis and Schizosaccharomyres pombe partially complement the respiratory-deficient phenotype of a S. cerevisiae QCR8-null mutant. This implies that the heterologous Qcr8 subunits can be imported by S. cerevisiae mitochondria and that they assemble to form a hybrid bc, complex that is sufficiently active to support growth. In contrast, the QCR8 gene from bovine heart, encoding the 9.5-kDa subunit, is not able to restore respiratory function to the S. cerevisiae null mutant. This lack of functional complementation is directly attributable to the inability of S. cerevisiae mitochondria to import this protein as shown by in vitro assays. However, a hybrid gene encoding the N-terminal 26 residues of S. cerevisiae subunit VIII and the rest of the 9.5-kDa bovine heart homologue, was able to functionally complement the QCR8-null mutant, albeit to a very low extent. Successful import into S. cerevisiae mitochondria was confirmed by in vitro import experiments. Surprisingly, although assembly of these hybrid complexes is reduced to an extent that is proportional to the evolutionary distance of the homologue to S. cerevisiae, the specific activities of the assembled complexes are the same as for the wild-type hc, complex. After solubilisation of the mitochondria1 membranes with the mild detergent dodecyl maltoside, the wild-type enzyme can be inactivated by incubation at increased temperature, independent of protease activity. The rate of inactivation can be significantly increased by the addition of o-phenanthroline [Boumans, H., Grivell, L. A. & Berden, J. A. (1997) J. Biol. Chem. 272, 16753-16760]. The hybrid complexes are much more sensitive to both types of treatment. We conclude that substitution of subunit VIII by a homologous counterpart results in a loosening of the structure of the be, complex on the intermembrane space side, resulting in a less stable insertion of the Rieske Fe-S protein in vivo and therefore a lower stability of the assembled enzyme under certain in vitro conditions, but without an effect on catalytic activity.

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“…hydrolysis (43). Newly imported polypeptides that fail to fold and assemble into a functional form are similarly instable inside the organelle (25).…”

Section: Fig 5 Efficient Degradation Of Both B 2 -Dhfr Proteins Depmentioning

confidence: 99%

The ClpB Homolog Hsp78 Is Required for the Efficient Degradation of Proteins in the Mitochondrial Matrix

Röttgers

Zufall²,

Guiard

et al. 2002

Journal of Biological Chemistry

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Molecular chaperones perform vital functions in mitochondrial protein import and folding. In yeast mitochondria, two members of the Clp/Hsp100 chaperone family, Hsp78 and Mcx1, have been identified as homologs of the bacterial proteins ClpB and ClpX, respectively. In this report we employed a novel quantitative assay system to assess the role of Hsp78 and Mcx1 in protein degradation within the matrix. Mitochondria were preloaded with large amounts of two purified recombinant reporter proteins exhibiting different folding stabilities. Proteolysis of the imported substrate proteins depended on the mitochondrial level of ATP and was mediated by the matrix protease Pim1/LON. Degradation rates were found to be independent of the folding stability of the reporter proteins. Mitochondria from hsp78⌬ cells exhibited a significant defect in the degradation efficiency of both substrates even at low temperature whereas mcx1⌬ mitochondria showed wild-type activity. The proteolysis defect in hsp78⌬ mitochondria was independent from the aggregation behavior of the substrate proteins. We conclude that Hsp78 is a genuine component of the mitochondrial proteolysis system required for the efficient degradation of substrate proteins in the matrix.

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The role of protein degradation in mitochondrial function and biogenesis

Cited by 103 publications

References 177 publications

Coordination of Nuclear and Mitochondrial Genome Expression during Mitochondrial Biogenesis in Arabidopsis

Coordination of Nuclear and Mitochondrial Genome Expression during Mitochondrial Biogenesis in Arabidopsis

The Role of Subunit VIII in the Structural Stability of the bc₁ Complex from Saccharomyces cerevisiae Studied Using Hybrid Complexes

The ClpB Homolog Hsp78 Is Required for the Efficient Degradation of Proteins in the Mitochondrial Matrix

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The role of protein degradation in mitochondrial function and biogenesis

Cited by 103 publications

References 177 publications

Coordination of Nuclear and Mitochondrial Genome Expression during Mitochondrial Biogenesis in Arabidopsis

Coordination of Nuclear and Mitochondrial Genome Expression during Mitochondrial Biogenesis in Arabidopsis

The Role of Subunit VIII in the Structural Stability of the bc1 Complex from Saccharomyces cerevisiae Studied Using Hybrid Complexes

The ClpB Homolog Hsp78 Is Required for the Efficient Degradation of Proteins in the Mitochondrial Matrix

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The Role of Subunit VIII in the Structural Stability of the bc₁ Complex from Saccharomyces cerevisiae Studied Using Hybrid Complexes