Nucleotide sequence and intron structure of the apocytochrome b gene of Neurospora crassa mitochondria.

Helmer‐Citterich, Manuela; Morelli, Giorgio; Macino, Giuseppe

doi:10.1002/j.1460-2075.1983.tb01575.x

Cited by 60 publications

(15 citation statements)

References 27 publications

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“…The c ob gene has been sequenced (30), and transcripts have been characterized in several laboratories (10,24,30). The longest characterized cob precursor was 4.8 kb long and contained two introns and a 5'-end extension of approximately 0.5 kb (Fig.…”

Section: Resultsmentioning

confidence: 99%

Development of an in vitro transcription system for Neurospora crassa mitochondrial DNA and identification of transcription initiation sites.

Kennell¹,

Lambowitz²

1989

Mol. Cell. Biol.

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We have developed an in vitro transcription system for Neurospora crassa mitochondrial DNA (mtDNA) and used it to identify transcription initiation sites at the 5' ends of the genes encoding the mitochondrial small and large rRNA and cytochrome b (cob). The in vitro transcription start sites correspond to previously mapped 5' ends of major in vivo transcripts of these genes. Sequences around the three transcription initiation sites define a 15-nucleotide consensus sequence, 5'-TTAGARA(T/G)G(T/G)ARTRR-3', all or part of which appears to be an element of an N. crassa mtDNA promoter. A somewhat looser 11-nucleotide consensus sequence, 5'-TTAGARR(T/G)R(T/G)A-3', was derived by including two additional promoters identified recently. Group I extranuclear mutants, such as [poky] and [SG-3], have a 4-base-pair (bp) deletion in the consensus sequence at the 5' end of the mitochondrial small rRNA and are grossly deficient in mitochondrial small rRNA (R. A. Akins and A. M. Lambowitz, Proc. Natl. Acad. Sci. USA 81:3791-3795, 1984). We show here that the 4-bp deletion in the consensus sequence decreases in vitro transcription from this site by more than 99%. N. crassa mtDNA is similar to Saccharomyces cerevisiae mtDNA in having multiple promoters, including separate promoters for the genes encoding the mitochondrial small and large rRNAs. Our results suggest that the primary effect of the 4-bp deletion in group I extranuclear mutants is to inhibit transcription of the mitochondrial small rRNA, leading to severe deficiency of mitochondrial small rRNA and small ribosomal subunits.

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Section: Resultsmentioning

confidence: 99%

Development of an in vitro transcription system for Neurospora crassa mitochondrial DNA and identification of transcription initiation sites.

Kennell¹,

Lambowitz²

1989

Mol. Cell. Biol.

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“…Gene organization in the cob-CO I-URFI region The gene localization in the cob-CO I-URFI region is shown in Figure 1. The following genes and open reading frames have been identified: cob (Helmer Citterich et al, 1983a;Burke et al, 1984), tRNACYs (this paper), the short unidentified reading frame URFU (Burger et al, 1982;Burger and Werner, 1983;, CO I (Burger et al, 1982;, the long unidentified reading frame URFN (in preparation), tRNAArg (Burger and Werner, 1983; this paper) and URFI (homologous to the corresponding human mitochondrial gene (Anderson et al, 1981;Burger et al, in preparation). Transfer RNA genes in the cob-CO I-URFI region Most of the tRNA genes encoded in the N. crassa mitochondrial genome are situated in several clusters near the genes for the small and large rRNAs (Green et al, 1981).…”

Section: Resultsmentioning

confidence: 99%

RNA processing in Neurospora crassa mitochondria: transfer RNAs punctuate a large precursor transcript.

Burger¹,

Helmer-Citterich²,

Nelson³

et al. 1985

The EMBO Journal

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The pattern of transcripts arising from a large contiguous portion of the Neurospora crassa mitochondrial genome and the processing of these transcripts have been investigated. Evidence is presented for the transcription of a single, at least 12.5 kb, precursor RNA that contains sequences corresponding to the apocytochrome b (cob), tRNACys, cytochrome oxidase subunit 1 (CO I), tRNAArg and unidentified reading frame (URF) 1 genes. The two tRNA sequences serve as punctuation signals for the cleavage of this large transcript. Processing at the tRNACys and tRNAArg sequences directly generates the proposed CO I mRNA, as well as the mature 3′ end of the cob transcripts. Moreover, three other sites have been identified that are specifically involved in further 5′ end processing events. One of the two 5′ end processing sites of the cob transcript shares homology with the 5′ end processing sites of the mitochondrial 19S and 25S rRNA precursors. PstI palindromes do not act as processing signals because six of these palindromic sequences are present in the cob and CO I mRNAs.

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“…Nucleotide sequence and codon usage The single long ORF of 1164 bp (Figure 3) is assumed to represent the maize COB gene since it displays 52 and 47% sequence homology with the COB genes in S. cerevisiae (Nobrega and Tzagoloff, 1980) and Homo sapiens , respectively. The gene does not appear to contain introns, in contrast with COB in many fungi (Nobrega and Tzagoloff, 1980;Waring et al, 1981;Citterich et al, 1983) and the COII gene in maize mitochondria (Fox and Leaver, 1981). However, because of the low amino acid sequence conservation at the amino and carboxy termini of the predicted polypeptides ( Figure 5, upper panel) the possibility that introns exist near the 5' and 3' ends of the gene cannot be formally excluded.…”

Section: Discussionmentioning

confidence: 98%

The apocytochrome b gene in maize mitochondria does not contain introns and is preceded by a potential ribosome binding site

1984

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The apocytochrome b (COB) gene has been isolated from maize (Zea mays L.) mitochondrial DNA. Sequence analysis reveals that the coding region of the gene is 1164 bp long and, in contrast with the homologous gene from yeast, does not contain introns or TGA (Trp) codons. The predicted polypeptide encoded by the gene has a mol. wt. of 42 868 daltons, and shows ˜48% amino acid sequence homology with the corresponding yeast and mammalian polypeptides. Hydropathic profiles of the polypeptide indicate the presence of nine, membrane spanning hydrophobic domains suggesting that it is organised in the inner mitochondrial membrane in a similar fashion to that proposed for apocytochrome b in other organisms. The COB gene is preceded by a sequence 5′ ‐AGTTGTCA‐3′ which may act as a ribosome binding site in the mRNA since: (i) it shows 67.5% complementarity with an octanucleotide at the 3′ end of the maize mitochondrial 18S rRNA, located in a position homologous to that of the Escherichia coli Shine and Dalgarno sequence, and (ii) a similar sequence precedes several other plant mitochondrial genes at a distance of 15–20 nucleotides from the ATG initiation codon. RNA transcript analysis shows that the gene is transcribed in a complex manner with the presumed mature mRNA (˜2.25 kb) probably being derived by sequential processing from a larger primary transcript.

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Nucleotide sequence and intron structure of the apocytochrome b gene of Neurospora crassa mitochondria.

Cited by 60 publications

References 27 publications

Development of an in vitro transcription system for Neurospora crassa mitochondrial DNA and identification of transcription initiation sites.

Development of an in vitro transcription system for Neurospora crassa mitochondrial DNA and identification of transcription initiation sites.

RNA processing in Neurospora crassa mitochondria: transfer RNAs punctuate a large precursor transcript.

The apocytochrome b gene in maize mitochondria does not contain introns and is preceded by a potential ribosome binding site

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