Synthesis and Assembly of Mitochondrial Proteins

Nicholson, Donald W.; Neupert, Walter

doi:10.1016/b978-0-12-203460-2.50021-4

Cited by 21 publications

(25 citation statements)

References 245 publications

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“…It containins 6 basic residues and no acidic residues. The carboxyl terminus of the presequence shows the motif Arg-Arg-Gly fol-lowed by leucine at position +l of the mature part, which is similar to the cleavage sites found in a number of other mitochondrial precursor proteins (Schmidt et al, 1984;Hart1 et al, 1986;Nicholson and Neupert, 1988). Indeed, the precursor of the 52 kd polypeptide expressed in vitro could be processed to the mature-sized protein by the purified processing enzyme (not shown).…”

Section: Characteristics Of the Purified Processing Enzymesupporting

confidence: 74%

Mitochondrial protein import: Identification of processing peptidase and of PEP, a processing enhancing protein

Hawlitschek

Schneider

Schmidt

et al. 1988

Cell

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376

185

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SummaryTransport of nuclear-encoded precursor proteins into mitochondria includes proteolytic cleavage of aminoterminal targeting sequences in the mitochondrial matrix. We have isolated the processing activity from Neurospora crassa. The final preparation (enriched ca. lO,OOO-fold over cell extracts) consists of two proteins, the matrix processing peptidase (MPP, 57 kd) and a processing enhancing protein (PEP, 52 kd). The two components were isolated as monomers. PEP is about l&fold more abundant in mitochondria than MPP It is partly associated with the inner membrane, while MPP is soluble in the matrix. MPP alone has a low processing activity whereas PEP alone has no apparent activity. Upon recombining both, full processing activity is restored. Our data indicate that MPP contains the catalytic site and that PEP has an enhancing function. The mitochondrial processing enzyme appears to represent a new type of "signal peptidase,' different from the bacterial leader peptidase and the signal peptidase of the endoplasmic reticulum.

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Section: Characteristics Of the Purified Processing Enzymesupporting

confidence: 74%

Mitochondrial protein import: Identification of processing peptidase and of PEP, a processing enhancing protein

Hawlitschek

Schneider

Schmidt

et al. 1988

Cell

Self Cite

376

185

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“…Apocytochrome c is able to penetrate the outer membrane without assistance of the receptor-GIP-complex and appears to be trapped in the intermembrane space after the covalent attachment of heme [47]. This process is catalysed by the enzyme cytochrome c heme lyase (CCHL), located on the surface of the inner membrane facing the intermembrane space.…”

Section: Bioenergetics Of Mitochondrial Protein Import and Sortingmentioning

confidence: 99%

Mitochondrial protein import: Mechanisms, components and energetics

Schwarz

Neupert

1994

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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The transport of nuclear-encoded proteins from the cytosol into mitochondria is mediated by targeting (signal) sequences present on precursor forms. Most precursors of the mitochondrial matrix possess amino-terminal signals which characteristically contain hydroxylated and basic amino acids and lack acidic residues. With a minority of precursor proteins, internal sequence motifs can direct proteins to the mitochondria (Planner, N., Hoeben, P., Tropschug, M. and Neupert, W. (1987) J. Biol. Chem. 262, 14851-14854). The presence of a mitochondrial targeting sequence alone, however, is not sufficient for specific targeting to the organeUe and further to the various subcompartments. There is the need for components which recognise the targeting sequences and others which keep the precursor protein in a translocation-competent form. Beyond the recognition step, components are required which mediate transiocation across the mitochondrial membranes. Mitochondria possess two translocation machineries, one in the outer membrane and one in the inner membrane. The matrix space harbors a number of factors which participate in the import of proteins, in their unfolding and folding. Energy is required at several steps of these processes.

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“…Precytochrome c=-DHFR is a fusion protein consisting of the signal sequence from cytochrome c~ fused to DHFR (66). matrix (for reviews see 14,25,45,52,59,69). The information that targets precursors to the mitochondria is usually encoded in a cleaved presequence, although some targeting and sorting information may reside in the mature protein (for review see 58).…”

Section: Abbreviations Used In This Papermentioning

confidence: 99%

In vitro import of cytochrome c peroxidase into the intermembrane space: release of the processed form by intact mitochondria.

Kaput

Brandriss

Prussak-Wieckowska

1989

The Journal of Cell Biology

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Abstract. Cytochrome c peroxidase (CCP) is a nuclearly encoded hemoprotein located in the intermembrane space (IMS) of Saccharomyces cerevisiae mitochondria. Wild-type preCCP synthesized in rabbit reticulocyte lysates, however, was inefficiently translocated into isolated mitochondria and was inherently resistant to externally added proteases. To test whether premature heme addition to the apoprecursor was responsible for the protease resistance and the inability to import preCCP, site-directed mutagenesis was used to replace the axial heme ligand (Hiss75) involved in forming a pseudo-covalent link between the heme iron and CCP. Mutant proteins containing Leu, Arg, Met, or Pro at residue 175 of mature CCP were sensitive to proteolysis and were imported into isolated mitochondria as judged by proteolytic processing of the precursor. The inhibition of wild-type CCP translocation across the outer membrane may result from the inability of the heme-containing protein to unfold during the translocation process.Although the protease responsible for cleaving preCCP to its mature form is believed to be located in the IMS, most of the processed CCP was located in the supernatant rather than the mitochondrial pellet. Since the outer membranes were shown to be intact, the anomalous localization indicated that preCCP may not have been completely translocated into the IMS before proteolytic processing or that conformationally labile proteins may not be retained by the outer membrane. Proteolytic maturation of preCCP also occurred in the presence of valinomycin, suggesting that the precursor may be completely or partially translocated across the outer mitochondrial membrane independent of a potential across the inner mitochondrial membrane. MOST mitochondrial proteins are encoded in the nucleus, synthesized as larger precursors in the cytoplasm (37), and then specifically targeted to one of four mitochondrial compartments: the outer membrane, the intermembrane space (IMS),~ the inner membrane, or the Portions of this work have appeared in abstract form (Brandriss, M. C., K.

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Synthesis and Assembly of Mitochondrial Proteins

Cited by 21 publications

References 245 publications

Mitochondrial protein import: Identification of processing peptidase and of PEP, a processing enhancing protein

Mitochondrial protein import: Identification of processing peptidase and of PEP, a processing enhancing protein

Mitochondrial protein import: Mechanisms, components and energetics

In vitro import of cytochrome c peroxidase into the intermembrane space: release of the processed form by intact mitochondria.

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