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Wolf K, Del Giudice L. The variable mitochondrial genome of ascomycetes: organization, mutational alterations, and expression. ADVANCES IN GENETICS 1988; 25:185-308. [PMID: 3057820 DOI: 10.1016/s0065-2660(08)60460-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- K Wolf
- Institut für Genetik und Mikrobiologie, Universität München, Munich, Federal Republic of Germany
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2
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Suyama Y. Two dimensional polyacrylamide gel electrophoresis analysis of Tetrahymena mitochondrial tRNA. Curr Genet 1986; 10:411-20. [PMID: 3127061 DOI: 10.1007/bf00418415] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Two dimensional (2D) urea-polyacrylamide gel electrophoresis of tRNA isolated from Tetrahymena mitochondria separated at least 36 spots, while more than 45 major and minor spots were resolved with cytosolic tRNA. Co-electrophoresis of mitochondrial and cytosolic tRNAs revealed that many spots co-migrate. When radioactive mitochondrial tRNA was hybridized to mtDNA under various conditions and tRNA melted from the hybrid was analyzed by 2D gel electrophoresis, only 10 tRNA spots were found. Identified as mtDNA-encoded were 2 spots for tRNA(leu), 2 for tRNA(met), and 1 each for tRNA(phe), tRNA(trp) and tRNA(tyr). The remaining three were unidentified. Mitochondrial tRNA spots that correspond to the tRNAs for arg, gly, ile, lys, ser, and val do not hybridize with mtDNA, and in gel positions they correspond to the cytoplasmic tRNA spots for the same respective amino acids. These mitochondrial tRNAs isolated from the gel can be acylated either by the mitochondrial or cytosolic enzymes. Mitochondrial tRNA isolated from a Tetrahymena cell homogenate which was pretreated with RNase A and Micrococcus nuclease exhibited the same 2D gel pattern as a non-treated control. Mitochondrial tRNAs from old and young cells showed generally similar tRNA spots in 2D gels, though more variable spots were seen with old cells. 3H-labeled whole-cell tRNA added to the cell homogenate prior to the mitochondrial isolation procedure did not remain associated with the final mitochondrial tRNA preparation. The present studies also showed mitochondrial tRNAs bound to the mitochondrial 80S monosome and polysome fractions. Radioactive tRNA added to the mitochondrial lysate does not adhere to the ribosomes, suggesting that the ribosome-bound tRNAs are not contaminating cytoplasmic tRNAs. These results are generally in good agreement with our previous data showing that only a small number of tRNAs are coded for by the mitochondrial DNA, while the others are a selected set of imported cytoplasmic tRNAs.
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Affiliation(s)
- Y Suyama
- Department of Biology, University of Pennsylvania, Philadelphia 19104
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3
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Garriga G, Bertrand H, Lambowitz AM. RNA splicing in Neurospora mitochondria: nuclear mutants defective in both splicing and 3' end synthesis of the large rRNA. Cell 1984; 36:623-34. [PMID: 6230156 DOI: 10.1016/0092-8674(84)90342-8] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We have identified nuclear mutants of Neurospora that are defective in splicing the mitochondrial large rRNA and that accumulate unspliced pre-rRNA (35S RNA). In cyt-4 mutants, the unspliced pre-rRNA contains short 3' end extensions (110 nucleotides) that are not present in pre-rRNAs from the other mutants. This and other characteristics suggest that the cyt-4 mutants may be primarily defective in 3' end synthesis and the RNA splicing defect occurs secondarily as a result of impaired RNA folding. The cyt-4 mutants also accumulate a "short" intron RNA and small exon RNAs that may reflect aberrant RNA cleavages. The 5' end of the short intron is about 285 nucleotides downstream from the 5' splice site at or near the base of the "central hairpin", a putative intermediate in folding of the pre-rRNA. Furthermore, the aberrant cleavage sites are immediately after a six nucleotide sequence (GAUAAU) homologous to the final splice junction (GAU/AAC).
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Wollenzien PL, Cantor CR, Grant DM, Lambowitz AM. RNA splicing in neurospora mitochondria: structure of the unspliced 35S precursor ribosomal RNA detected by psoralen cross-linking. Cell 1983; 32:397-407. [PMID: 6825174 DOI: 10.1016/0092-8674(83)90459-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The structure of the unspliced 35S precursor rRNA of Neurospora mitochondria was studied by psoralen photochemical cross-linking. The results show that when the 35S RNA is cross-linked in ribonucleoprotein particles (RNPs) under appropriate conditions, the predominant configuration is a 2.2 kb intron loop which brings opposite splice sites into proximity; that the predominant secondary structural feature in the free RNA is a relatively large hairpin (length = 0.105 kb) in the center of the molecule at or near the 5' splice site; that the intron loop and the central hairpin are different configurations of sequences at or near the 5' splice site; and that the intron loop is stabilized by protein components of RNPs. Based on the structures detected by psoralen photochemical cross-linking, we propose a mechanism for the splicing of the Neurospora mitochondrial precursor rRNA. We propose further that certain features of this mechanism may be relevant to the splicing of other RNAs, including eucaryotic mRNAs.
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Eperon IC, Janssen JW, Hoeijmakers JH, Borst P. The major transcripts of the kinetoplast DNA of Trypanosoma brucei are very small ribosomal RNAs. Nucleic Acids Res 1983; 11:105-25. [PMID: 6306559 PMCID: PMC325693 DOI: 10.1093/nar/11.1.105] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The nucleotide sequence has been determined of a 2.2 kb segment of kinetoplast DNA, which encodes the major mitochondrial transcripts (12S and 9S) of Trypanosoma brucei. The sequence shows that the 12S RNA is a large subunit rRNA, although sufficiently unusual for resistance to chloramphenicol to be predicted. The 9S RNA has little homology with other rRNAs, but a possible secondary structure is not unlike that of the 2.5-fold larger E. coli 16S rRNA. We conclude that the 12S RNA (about 1230 nucleotides) and the 9S RNA (about 640 nucleotides) are the smallest homologues of the E. coli 23S and 16S rRNAs yet observed.
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Collins RA, Lambowitz AM. Structural variations and optional introns in the mitochondrial DNAs of Neurospora strains isolated from nature. Plasmid 1983; 9:53-70. [PMID: 6300945 DOI: 10.1016/0147-619x(83)90031-8] [Citation(s) in RCA: 73] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mitochondrial DNAs from ten wild-type Neurospora crassa, Neurospora intermedia, and Neurospora sitophila strains collected from different geographical areas were screened for structural variations by restriction enzyme analysis. The different mtDNAs show much greater structural diversity, both within and among species, than had been apparent from previous studies of mtDNA from laboratory N. crassa strains. The mtDNAs range in size from 60 to 73 kb, and both the smallest and largest mtDNAs are found in N. crassa strains. In addition, four strains contain intramitochondrial plasmid DNAs that do not hybridize with the standard mtDNA. All of the mtDNA species have a basically similar organization. A 25-kb region that includes the rRNA genes and most tRNA genes shows very strong conservation of restriction sites in all strains. The 2.3-kb intron found in the large rRNA gene in standard N. crassa mtDNAs is present in all strains examined, including N. intermedia and N. sitophila strains. The size differences between the different mtDNAs are due to insertions or deletions that occur outside of the rRNA-tRNA region. Restriction enzyme and heteroduplex mapping suggest that four of these insertions are optional introns in the gene encoding cytochrome oxidase subunit I. Mitochondrial DNAs from different wild-type strains contain zero, one, three, or four of these introns.
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7
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Tabak HF, Grivell LA, Borst P. Transcription of mitochondrial DNA. CRC CRITICAL REVIEWS IN BIOCHEMISTRY 1983; 14:297-317. [PMID: 6196153 DOI: 10.3109/10409238309102797] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
While mitochondrial DNA (mtDNA) is the simplest DNA in nature, coding for rRNAs and tRNAs, results of DNA sequence, and transcript analysis have demonstrated that both the synthesis and processing of mitochondrial RNAs involve remarkably intricate events. At one extreme, genes in animal mtDNAs are tightly packed, both DNA strands are completely transcribed (symmetric transcription), and the appearance of specific mRNAs is entirely dependent on processing at sites signalled by the sequences of the tRNAs, which abut virtually every gene. At the other extreme, gene organization in yeast (Saccharomyces) is anything but compact, with long stretches of AT-rich DNA interspaced between coding sequences and no obvious logic to the order of genes. Transcription is asymmetric and several RNAs are initiated de novo. Nevertheless, extensive RNA processing occurs due largely to the presence of split genes. RNA splicing is complex, is controlled by both mitochondrial and nuclear genes, and in some cases is accompanied by the formation of RNAs that behave as covalently closed circles. The present article reviews current knowledge of mitochondrial transcription and RNA processing in relation to possible mechanisms for the regulation of mitochondrial gene expression.
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8
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Burke JM, RajBhandary UL. Intron within the large rRNA gene of N. crassa mitochondria: a long open reading frame and a consensus sequence possibly important in splicing. Cell 1982; 31:509-20. [PMID: 6218884 DOI: 10.1016/0092-8674(82)90307-5] [Citation(s) in RCA: 161] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We describe the sequence of the 2295 nucleotide long intron and 245 nucleotides of the flanking exon sequences within the large (24S) rRNA gene of Neurospora crassa mitochondria. The intron contains a long open reading frame, which could correspond to ribosomal protein S5. Comparison with the corresponding intron of the large rRNA gene of yeast mitochondria reveals a single highly homologous 57 nucleotide long sequence, including the sequence (formula; see text), which is present in virtually all the sequenced introns of yeast, Aspergillus nidulans and Zea mays mitochondrial genes, and which may be important for their processing. Sequences closely related to this consensus sequence are also present within all four of the introns of nuclear rRNA genes which have been sequenced. The intron is located within a highly conserved region of the large rRNA sequence and at exactly the same site as in the corresponding introns in yeast mitochondria and also in Physarum polycephalum nuclei.
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Tu J, Zillig W. Organization of rRNA structural genes in the archaebacterium Thermoplasma acidophilum. Nucleic Acids Res 1982; 10:7231-45. [PMID: 7155894 PMCID: PMC327000 DOI: 10.1093/nar/10.22.7231] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In the archaebacterium Thermoplasma acidophilum, each of the structural genes for 5S, 16S and 23S rRNA occur once per genome. In contrast to those of eubacteria and eukaryotes, they appear unlinked. The distance between the 16S and the 23S rDNA is at least 7.5 Kb, that between 23S and 5S rDNA at least 6 Kb and that between 16S and 5S rDNA at least 1.5 Kb. No linkage between those genes has been found by the analysis of recombinant plasmids carrying Bam HI and Hind III rDNA fragments as by hybridizing those plasmids to fragments of Thermoplasma DNA generated by 6 individual restriction endonucleases, recognizing hexanucleotide sequences.
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Bertrand H, Bridge P, Collins RA, Garriga G, Lambowitz AM. RNA splicing in Neurospora mitochondria. Characterization of new nuclear mutants with defects in splicing the mitochondrial large rRNA. Cell 1982; 29:517-26. [PMID: 7116448 DOI: 10.1016/0092-8674(82)90168-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In Neurospora, the gene encoding the mitochondrial large (25S) ribosomal RNA contains an intervening sequence of 2.3 kb. We have identified eight nuclear mutants that are defective in splicing the mitochondrial large ribosomal RNA and that accumulate unspliced precursor RNA. These mutants identify three different nuclear genes required for the same mitochondrial RNA splicing reaction. Some of the mutants have unique phenotypic characteristics (for example, accumulation of an unusual intron RNA) that may provide insight into specific aspects of mitochondrial RNA splicing. Mutations at one locus, cyt4, are subject to partial phenotypic suppression by the electron-transport inhibitor antimycin. This phenomenon suggests that at least one component required for mitochondrial RNA splicing is regulated such that its synthesis or activity is increased in response to impairment of electron transport.
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Yin S, Heckman J, RajBhandary UL. Highly conserved GC-rich palindromic DNA sequences flank tRNA genes in Neurospora crassa mitochondria. Cell 1981; 26:325-32. [PMID: 6276013 DOI: 10.1016/0092-8674(81)90201-4] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In sequencing a 2200 bp region of the Neurospora crassa mitochondrial DNA encoding the 3' end of the large rRNA gene and a cluster of six tRNA genes, we have found that the tRNA genes are flanked by highly conserved GC-rich palindromic DNA sequences. An 18 bp long core sequence, 5'-CC CTGCAG TA CTGCAG GG-3', containing two closely spaced Pst I sites, is common to all these palindromic sequences. Each of the eight Pst I sites mapped in the 2200 bp region consists of two closely spaced Pst I sites; thus this 2200 bp long segment actually contains 16 Pst I sites. Between 5-10% of the N. crassa DNA may consist of these GC-rich palindromic sequences that include the 18 base long core sequence. The same core sequence is present within both the 5' and 3' side of the intervening sequence of the large rRNA gene, close to, but not at, the intron-exon boundaries. We discuss probable roles for these sequences in N. crassa mitochondrial function, including their role as signals either in the synthesis or processing (or both) of RNA in the mitochondria.
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14
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Collins RA, Lambowitz AM. Characterization of a variant Neurospora crassa mitochondrial DNA which contains tandem reiterations of a 1.9 kb sequence. Curr Genet 1981; 4:131-3. [DOI: 10.1007/bf00365691] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/1981] [Indexed: 10/26/2022]
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15
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Lazarus CM, K�ntzel H. Anatomy of amplified mitochondrial DNA in ?Ragged? mutants of Aspergillus amstelodami: Excision points within protein genes and a common 215 bp segment containing a possible origin of replication. Curr Genet 1981; 4:99-107. [DOI: 10.1007/bf00365688] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/1981] [Indexed: 11/27/2022]
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16
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Grimm MF, Cole MD, Lambowitz AM. Ribonucleic acid splicing in Neurospora Mitochondria: secondary structure of the 35S ribosomal precursor ribonucleic acid investigated by digestion with ribonuclease III and by electron microscopy. Biochemistry 1981; 20:2836-42. [PMID: 6264946 DOI: 10.1021/bi00513a020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In Neurospora, the gene encoding the mitochondrial large (25S) ribosomal ribonucleic acid (rRNA) contains an intervening sequence of approximately 2.3 kilobases (kb). We have identified two temperature-sensitive mutants (289-67 and 299-9) which are defective in a factor encoded by a nuclear gene but required for the splicing of 25S RNA. When grown at the nonpermissive temperature (37 degrees C), the mutants accumulate a novel 35S RNA (5.2-5.6 kb) which is related to the natural precursor of 25S RNA and which has been shown to be a collinear transcript of the 25S RNA gene including the intervening sequence. In the present work, the secondary structure of 35S RNA was investigated by digestion with ribonuclease III and by electron microscopy of the RNA spread under partially denaturing conditions. Ribonuclease III cleaves 35S RNA predominantly at a central site or sites near the 5'-intron-exon boundary and produces fragments which correspond roughly to half-molecules (2.5-3 kb). Electron microscopy of 35S RNA shows a relatively large, central hairpin (180 +/- 45 nucleotides), which presumably corresponds to the central ribonuclease III site, and few other secondary structure features. Both experimental approaches indicate that the large hairpin is not present in 35S RNA. From this finding and from the location of the hairpin near the 5'-intron-exon boundary in 35S RNA, we infer that its formation requires intron sequences. 35S RNA from the mutants can be isolated as a ribonucleoprotein particle associated with almost the full complement of large subunit ribosomal proteins. The 35S RNA in such particles can be cleaved by ribonuclease III at the central site(s), consistent with the idea that the central hairpin is accessible to RNA-processing enzymes in vivo.
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17
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Roiha H, Miller JR, Woods LC, Glover DM. Arrangements and rearrangements of sequences flanking the two types of rDNA insertion in D. melanogaster. Nature 1981; 290:749-53. [PMID: 6783966 DOI: 10.1038/290749a0] [Citation(s) in RCA: 150] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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18
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Transcripts and processing patterns for the ribosomal RNA and transfer RNA region of Neurospora crassa mitochondrial DNA. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69911-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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19
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Köchel HG, Lazarus CM, Basak N, Küntzel H. Mitochondrial tRNA gene clusters in Aspergillus nidulans: organization and nucleotide sequence. Cell 1981; 23:625-33. [PMID: 7008953 DOI: 10.1016/0092-8674(81)90158-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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20
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Cedergren RJ, Sankoff D, LaRue B, Grosjean H. The evolving tRNA molecule. CRC CRITICAL REVIEWS IN BIOCHEMISTRY 1981; 11:35-104. [PMID: 7030617 DOI: 10.3109/10409238109108699] [Citation(s) in RCA: 74] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The study of tRNA molecular evolution is crucial to understanding the origin and establishment of the genetic code as well as the differentiation and refinement of the machinery of protein synthesis in prokaryotes, eukaryotes, organelles, and phage systems. The small size of the molecule and its critical involvement in a multiplicity of roles distinguish its study from classical protein molecular evolution with respect to goals and methods. Here, the authors assess available and missing data, existing and needed methodology, and the impact of tRNA studies on current theories both of genetic code evolution and of the evolution of species. They analyze mutational "hot spots", the role of base modification, synthetase recognition, codon-anticodon interactions and the status of organelle tRNA.
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Bertrand H, Collins RA, Stohl LL, Goewert RR, Lambowitz AM. Deletion mutants of Neurospora crassa mitochondrial DNA and their relationship to the "stop-start" growth phenotype. Proc Natl Acad Sci U S A 1980; 77:6032-6. [PMID: 6449700 PMCID: PMC350207 DOI: 10.1073/pnas.77.10.6032] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
"Stoppers" are a class of Neurospora crassa extranuclear mutants characterized by gross deficiencies of cytochromes b and aa3 and an unusual growth phenotype which involves irregular periods of growth andnongrowth. In the present work, mtDNAs from all four stopper mutants were found to contain deletions or insertions detectable by restriction enzyme analysis. [stp] mtDNA consists predominantly of defective molecules which retain a 16-megadalton segment (EcoRI-1, -4, and -6) of wild-type mtDNA (40 megadaltons). The other stopper mutants show smaller alterations: [stp A18t]-618, a 0.35-kilobase deletion in EcoRI-7b; [stp B2]-651, a 4-kilobase insertion in EcoRI-2; and [stp A]-574, a 5-kilobase deletion in EcoRI-2 and -10. Based on these results, we propose that "stop-start" growth results from competition between certain defective mtDNAs which have a tendency to predominate and low concentrations of less defective mtDNA species which must be retained to sustain growth. Three additional extranuclear mutants ("nonstoppers") have also been found to contain deletions in mtDNA. Remarkably, the defective mtDNA species in two of these mutants ([poky]H1-10 and [SG-3]-551) retain different sizes (18 and 13 megadlatons, respectively) of the same region retained in [stp] mtDNA (i.e., EcoRI-1, -4, and -6). The findings suggest that production of defective mtDNAs in Neurospora is nonrandom with a preferred mechanism leading to retention of this segment. It may be significant that the retained segment contains both mitochondrial rRNA genes and most mitochondrial tRNA genes. These deletion mutants may provide a tool for genetic mapping of Neurospora mtDNA.
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Dujon B. Sequence of the intron and flanking exons of the mitochondrial 21S rRNA gene of yeast strains having different alleles at the omega and rib-1 loci. Cell 1980; 20:185-97. [PMID: 6156002 DOI: 10.1016/0092-8674(80)90246-9] [Citation(s) in RCA: 329] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The complete nucleotide sequence has been determined for the intron, its junctions and the flanking exon regions of the 21S rRNA gene in three genetically characterized strains differing by their omega alleles (omega+, omega- and omega n) and by their chloramphenicol-resistant mutations at the rib-1 locus. Comparison of these DNA sequences shows that: --omega+ differs from omega- and omega n by the presence of the intron (1143 bp), as well as by a second and unexpected mini-insert (66 bp) located 156 bp upstream within the exon, whose nature and functions are still unknown but whose striking palindromic structure may suggest a mitochondrial transposable element. --The two mutations C321R and C323R correspond to two different monosubstitutions, 56 bp apart in the omega- and omega n strains but separated by the intron in the omega+ strains. In relation to previous genetic results, a model is discussed assuming that the interactions of two different regions or genetic loci determine the chloramphenicol resistance, one of which contains the omega n mutations. --A long uninterrupted coding sequence able to specify a 235 amino acid polypeptide exists within the intron. This remarkable observation gives new insight into the origin of the mitochondrial introns and raises the question of the possible functions of intron-encoded polypeptides. Finally, sequence comparisons with evolutionarily distant organisms, showing that different rRNA introns are inserted at different positions of an otherwise highly conserved region of the gene, suggest a recent insertion of these introns and a mechanism for splicing after the assembly of the large ribosomal subunit.
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25
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Groot GSP, Van Harten-Loosbroek N. The organization of the genes for ribosomal RNA on mitochondrial DNA of Kluyveromyces lactis. Curr Genet 1980; 1:133-5. [DOI: 10.1007/bf00446959] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/1979] [Indexed: 11/30/2022]
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26
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Bonen L, Gray MW. Organization and expression of the mitochondrial genome of plants I. The genes for wheat mitochondrial ribosomal and transfer RNA: evidence for an unusual arrangement. Nucleic Acids Res 1980; 8:319-35. [PMID: 6252544 PMCID: PMC327269 DOI: 10.1093/nar/8.2.319] [Citation(s) in RCA: 80] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We show here that mitochondrial-specific ribosomal and transfer RNAs of wheat (Triticum vulgare Vill. [Triticum aestivum L.] var. Thatcher) are encoded by the mitochondrial DNA (mtDNA). Individual wheat mitochondrial rRNA species (26S, 18S, 5S) each hybridized with several mtDNA fragments in a particular restriction digest (Eco RI, Xho I, or Sal I). In each case, the DNA fragments to which 18S and 5S rRNAs hybridized were the same, but different from those to which 26S rRNA hybridized. From these results, we conclude that the structural genes for wheat mitochondrial 18S and 5S rRNAs are closely linked, but are physically distant from the genes for wheat mitochondrial 26S rRNA. This arrangement of rRNA genes is clearly different from that in prokaryotes and chloroplasts, where 23S, 16S and 5S rRNA genes are closely linked, even though wheat mitochondrial 18S rRNA has previously been shown to be prokaryotic in nature. The mixed population of wheat mitochondrial 4S RNAs (tRNAs) hybridized with many large restriction fragments, indicating that the tRNA genes are broadly distributed throughout the mitochondrial genome, with some apparent clustering in regions containing 18S and 5S rRNA genes.
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27
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Mannella CA, Goewert RR, Lambowitz AM. Characterization of variant Neurospora crassa mitochondrial DNAs which contain tandem reiterations. Cell 1979; 18:1197-207. [PMID: 160287 DOI: 10.1016/0092-8674(79)90232-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Two variant mtDNA types ((types IIa and HI-10) have been identified in individual subcultures of the extra-nuclear [poky] mutant of Neurospora crassa. Eco RI digests of type IIa mtDNA are characterized by an extra band, alpha, Mr = 1.4 Mdal, which arises from tandemly inserted reiterations of a 1.4 Mdal sequence. Restriction enzyme analysis and Southern hybridization experiments show: that the 1.4 Mdal repeats are located at the junction of Eco RI-4 and -6, that the repeats contain sequences ordinarily present in Eco RI-4 and -6, that the repeats are oriented head-to-tail and that the number of repeats per molecule (n) varies from n = 0 to n = 8, with about half of the molecules containing no repeats. The 1.4 Mdal repeats appear to be actively mained in type IIa mtDNA populations as a result of a specific alteration in mtDNA. Data are presented which suggest that this alteration may be located near small deletions and/or sequence changes in Eco RI-3 and -10, fragments almost exactly opposite the site of the repeats on the genome. The second variant, HI-10 mtDNA, arose in a heteroplasmic strain in which type IIa mtDNA was one component. The most striking feature of HI-10 mtDNA is the up to 5-fold amplification of an 18 Mdal segment extending from Eco RI-4 (the site of the 1.4 Mdal repeats) through the rRNA genes. Eco RI digests show that HI-10 possesses characteristic features of type IIa mtDNA, including the 1.4 Mdal repeats and the alteration in Eco RI-10. HI-10 mtDNA also shows a novel Eco RI fragment, beta, Mr = 2.9 Mdal. The variant Neurospora mtDNAs may be generated by mechanisms analogous to those which give rise to defective mtDNAs of yeast petite mutants. The possible consequences of defective mtDNAs in obligately aerobic organisms are discussed.
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28
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Heckman J, Yin S, Alzner-DeWeerd B, RajBhandary U. Mapping and cloning of Neurospora crassa mitochondrial transfer RNA genes. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(19)86369-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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29
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Binding of mitochondrial ribosomal proteins to a mitochondrial ribosomal precursor RNA containing a 2.3-kilobase intron. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(19)86546-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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