A crucial role of the mitochondrial protein import receptor MOM19 for the biogenesis of mitochondria

Harkness, Troy A. A.; Nargang, Frank E.; Klei, van der Ida; Neupert, Walter; Lill, Roland

doi:10.1083/jcb.124.5.637

Cited by 106 publications

(100 citation statements)

References 52 publications

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“…grown and maintained under standard conditions [24]. Mitochondria were freshly isolated prior to each import experiment [25]. Radiolabelled porin preproteins were synthesized by coupled in vitro transcription/translation (TNT SP6 coupled reticulocyte lysate system, Promega) in the presence of [35S]methionine (ICN Radiochemicals) as label.…”

Section: Construction Of Porin Mutantsmentioning

confidence: 99%

“…To ascertain whether A2-12porin and A3-20porin, like the wild-type protein, utilize the TOM complex during their import, these preproteins were imported into mitochondria that were pretreated with IgGs raised against Tom20, a receptor component that is utilized by porin [25,28]. The import of the N-terminally truncated porins was inhibited by these IgGs (Fig.…”

Section: Da Court Et Al/febs Letters 390 (1996) 73-77mentioning

confidence: 99%

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Role of the N‐ and C‐termini of porin in import into the outer membrane of Neurospora mitochondria

et al. 1996

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The signals for targeting and assembly of porin, a protein of the mitochondrial outer membrane, have not been clearly defined. Targeting information has been hypothesized to be contained in the N-terminus, which may form an amphipathic a-helix, and in the C-terminal portion of the protein. Here, the role of the extreme N-and C-termini of porin from Neurospora crassa in its import into the mitochondrial outer membrane was investigated. Deletion mutants were constructed which lacked the N-terminal 12 or 20 residues or the C-terminal 15 residues. The porins truncated at their N-termini were imported in a receptordependent manner into the outer membrane of isolated mitochondria. When integrated into the outer membrane, these preproteins displayed an increased sensitivity to protease as compared to wild-type porin. In contrast, mutant porin truncated at its C-terminus did not acquire protease resistance upon incubation with mitochondria. Thus, unlike most other mitochondrial preproteins, porin appears to contain important targeting and/or assembly information at its C-terminus, rather than at the N-terminus.

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Section: Construction Of Porin Mutantsmentioning

confidence: 99%

Section: Da Court Et Al/febs Letters 390 (1996) 73-77mentioning

confidence: 99%

Role of the N‐ and C‐termini of porin in import into the outer membrane of Neurospora mitochondria

et al. 1996

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“…Inactivation of the N. crassa MOM19 gene has recently been achieved by a novel technique designed to introduce mutations into N. crassa genes [8]. The characterisation of these mutant N. crassa cells demonstrated the important role of MOM19 in precursor import: cells in which the MOM19 gene was inactivated stopped to grow, the mitochondria lost their protein synthesis activity as well as their respiratory complexes [9]. Lysis of N. crassa mitochondria with mild detergents and subsequent immunoprecipitation with anti-MOM19 antibodies revealed that MOM19 is present in a complex with MOM72 and a number of other proteins of 7, 8, 22 and 38 kDa (MOM7, MOM8, MOM22 and MOM38) [10].…”

Section: The Receptor Complex Of the Outer Membranementioning

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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“…The TOM complex contains components that expose domains to the cytosol and function as preprotein receptors. The major receptor is Tom20, which is involved, together with Tom22, in the translocation of most precursors (5)(6)(7). Another receptor that forms a binding site for a more restricted set of preproteins, most notably the mitochondrial carrier family, is Tom70 (8,9).…”

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confidence: 99%

Assembly of Tom6 and Tom7 into the TOM Core Complex ofNeurospora crassa

Dembowski

Künkele

Nargang

et al. 2001

Journal of Biological Chemistry

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Translocation of preproteins across the mitochondrial outer membrane is mediated by the translocase of the outer mitochondrial membrane (TOM) complex. We report the molecular identification of Tom6 and Tom7, two small subunits of the TOM core complex in the fungus Neurospora crassa. Cross-linking experiments showed that both proteins were found to be in direct contact with the major component of the pore, Tom40. In addition, Tom6 was observed to interact with Tom22 in a manner that depends on the presence of preproteins in transit. Precursors of both proteins are able to insert into the outer membrane in vitro and are assembled into authentic TOM complexes. The insertion pathway of these proteins shares a common binding site with the general import pathway as the assembly of both Tom6 and Tom7 was competed by a matrix-destined precursor protein. This assembly was dependent on the integrity of receptor components of the TOM machinery and is highly specific as in vitro-synthesized yeast Tom6 was not assembled into N. crassa TOM complex. The targeting and assembly information within the Tom6 sequence was found to be located in the transmembrane segment and a flanking segment toward the N-terminal, cytosolic side. A hybrid protein composed of the C-terminal domain of yeast Tom6 and the cytosolic domain of N. crassa Tom6 was targeted to the mitochondria but was not taken up into TOM complexes. Thus, both segments are required for assembly into the TOM complex. A model for the topogenesis of the small Tom subunits is discussed.

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A crucial role of the mitochondrial protein import receptor MOM19 for the biogenesis of mitochondria

Cited by 106 publications

References 52 publications

Role of the N‐ and C‐termini of porin in import into the outer membrane of Neurospora mitochondria

Role of the N‐ and C‐termini of porin in import into the outer membrane of Neurospora mitochondria

Mitochondrial protein import: Mechanisms, components and energetics

Assembly of Tom6 and Tom7 into the TOM Core Complex ofNeurospora crassa

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