The mitochondrially made subunit 2 of Neurospora crassa cytochrome aa3 is synthesized as a precursor protein

Boogaart, Paul van den; Dijk, Simon van; Agsteribbe, E

doi:10.1016/0014-5793(82)81019-3

Cited by 23 publications

(2 citation statements)

References 19 publications

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“…the mitochondrial inner membrane or the intermembrane space. In certain cases mitochondrially encoded proteins have sorting sequences, for instance subunits I and II of cytochrome-c oxidase from N. crassa [44,45]. Some nucleus-encoded mitochondrial proteins have presequences with sorting domains (bipartite signal sequences), e.g.…”

Section: Discussionmentioning

confidence: 99%

Subunit VII of ubiquinol:cytochrome-c oxidoreductase from Neurospora crassa is functional in yeast and has an N-terminal extension that is not essential for mitochondrial targeting

Lôbo-Hajdu

Braun

Romp

et al. 1996

Biochemical Journal

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cDNA clones encoding subunit VII of the Neurospora crassa bc1 complex (ubiquinol:cytochrome-c oxidoreductase), which is homologous with subunit VIII of the complex from yeast (encoded by QCR8), were identified on the basis of functional complementation of a yeast QCR8 deletion strain. The clones contain an open reading frame encoding a protein with a calculated molecular mass of 11.8 kDa. The N-terminal eight residues of the amino acid sequence deduced from the cDNA clones are absent from the mature protein, as revealed by direct sequencing of the isolated protein. To investigate the potential role of the N-terminal octapeptide in mitochondrial targeting, constructs were made encoding the precursor and the mature form of subunit VII from Neurospora. Incubation of isolated mitochondria with the two proteins revealed that the N-terminal extension of the precursor is removed on import. However, the presequence does not encode information for targeting, as the proteins encoded by both constructs can be imported into isolated mitochondria with equal efficiency. In contrast, the octapeptide seems to have functional importance: the defect in the yeast qcr8-null mutant is not complemented on transformation with the construct encoding mature subunit VII from N. crassa in a single-copy plasmid. We therefore speculate that the N-terminal extension plays a role in intramitochondrial sorting of N. crassa subunit VII. This is supported by the fact that the subunit VII precursor is processed by a protease other than the general mitochondrial processing peptidase. Interestingly, the presequence of N. crassa subunit VII has an amino acid composition similar to the octapeptides cleaved off by the mitochondrial intermediate peptidase.

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Section: Discussionmentioning

confidence: 99%

Subunit VII of ubiquinol:cytochrome-c oxidoreductase from Neurospora crassa is functional in yeast and has an N-terminal extension that is not essential for mitochondrial targeting

Lôbo-Hajdu

Braun

Romp

et al. 1996

Biochemical Journal

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“…1. Parts of the base sequence of this region have been published previously (3)(4)(5)19 2). Transcript analyses by Northern hybridization of intragenic DNA fragments to filter-blotted total mitochondrial RNA reveal that the three genes exhibit complementarity to a great number of transcripts ( fig.…”

Section: Resultsmentioning

confidence: 99%

Processing of precursor RNAs from mitochondria ofNeurospora crassa

Agsteribbe

Hartog

1987

Nucl Acids Res

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Neurospora mitochondrial DNA is transcribed into long molecules containing the information of several genes. Processing leads to formation of functionally active RNAs. It has been shown previously that when tRNA sequences are present in these transcripts excision of mRNAs occurs at the acceptor stem of these tRNA sequences. We have investigated the processing of precursor RNAs transcribed from a region of the mitochondrial genome devoid of tRNA genes. This region comprises the genes encoding subunit 6 of the mitochondrial ATPase, subunit 2 of cytochrome aa3 and a mitochondrial ATPase proteolipid-like gene. We have proved that a common precursor of the putative mRNAs of these genes exists and we have determined the positions of the 5' and 3' ends of processing intermediates and of the mature mRNAs. We will discuss possible processing routes and secondary structures that substitute for tRNA sequences as processing sites.

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A nuclear mutation prevents processing of a mitochondrially encoded membrane protein in Saccharomyces cerevisiae.

Pratje¹,

Mannhaupt²,

Michaelis³

et al. 1983

The EMBO Journal

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Subunit II of cytochrome oxidase is encoded by the mitochondrial OXI1 gene in Saccharomyces cerevisiae. The temperature‐sensitive nuclear pet mutant ts2858 has an apparent higher mol. wt. subunit II when analyzed on lithium dodecylsulfate (LiDS) polyacrylamide gels. However, on LiDS‐6M urea gels the apparent mol. wt. of the wild‐type protein exceeds that of the mutant. Partial revertants of mutant ts2858 that produce both the wild‐type and mutant form of subunit II were isolated. The two forms of subunit II differ at the N‐terminal part of the molecule as shown by constructing and analyzing nuclear ts2858 and mitochondrial chain termination double mutants. The presence of the primary translation product in the mutant and of the processed form in the wild‐type lacking 15 amino‐terminal residues was demonstrated by radiolabel protein sequencing. Comparison of the known DNA sequence with the partial protein sequence obtained reveals that six of the 15 residues are hydrophilic and, unlike most signal sequences, this transient sequence does not contain extended hydrophobic parts. The nuclear mutation ts2858 preventing post‐translational processing of cytochrome oxidase subunit II lies either in the gene for a protease or an enzyme regulating a protease.

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The mitochondrially made subunit 2 of Neurospora crassa cytochrome aa₃ is synthesized as a precursor protein

Cited by 23 publications

References 19 publications

Subunit VII of ubiquinol:cytochrome-c oxidoreductase from Neurospora crassa is functional in yeast and has an N-terminal extension that is not essential for mitochondrial targeting

Subunit VII of ubiquinol:cytochrome-c oxidoreductase from Neurospora crassa is functional in yeast and has an N-terminal extension that is not essential for mitochondrial targeting

Processing of precursor RNAs from mitochondria ofNeurospora crassa

A nuclear mutation prevents processing of a mitochondrially encoded membrane protein in Saccharomyces cerevisiae.

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