Mitochondrial plasmids of neurospora: Integration into mitochondrial DNA and evidence for reverse transcription in mitochondria

Akins, Robert A.; Kelley, Robert; Lambowitz, Alan M.

doi:10.1016/0092-8674(86)90615-x

Cited by 128 publications

(84 citation statements)

References 34 publications

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“…The latter are thought to be analogous to GC-rich clusters, which have been shown to be mobile in yeast mtDNA (36,37). Likewise, both linear and circular mitochondrial plasmids have previously been shown to integrate into Neurospora mtDNA (9,11,(38)(39)(40).…”

Section: Discussionmentioning

confidence: 99%

“…Transcription around the plasmid coupled with this RNA cleavage generates the full-length linear transcripts shown below, with the indicated 5′-and 3′-end sequences. The TRL-64 or TRL-78 sequences are inserted in the suppressive mutant plasmids between the positions corresponding to the 5′-and 3′-ends of the major plasmid transcript (9)(10)(11). In pV34-14, the insertion of TRL-78 is accompanied by deletion of a 24-nt sequence corresponding to the 5′-end of the wild-type plasmid transcript, identical to the deletion found associated with several mt tRNA insertions (10).…”

Section: Neurospora Strains and Growth Conditionsmentioning

confidence: 99%

“…3720). Senescent mutant V1-2 was described previously (9). A collection of wild-type strains and natural isolates that was surveyed for the TRL sequence is Figure 1.…”

Section: Neurospora Strains and Growth Conditionsmentioning

confidence: 99%

“…The suppressive plasmid found in the Varkud variant V1-2 was unusual in that it had incorporated a novel 64-nt sequence (TRL-64) that could fold into a cloverleaf structure but did not correspond to a conventional mt tRNA (9,10). We subsequently isolated two additional suppressive plasmids (V51-6a and V34-14) that incorporated a longer form of this tRNA-like sequence (TRL-78) containing a 14-nt insertion in the anticodon stem at a position reminiscent of a nuclear tRNA intron (11).…”

Section: Introductionmentioning

confidence: 99%

“…When the plasmid-containing strains are subjected to prolonged vegetative growth, suppressive variants of the plasmids arise that out-compete the wild-type plasmid and mtDNA, leading to progressively impaired growth and ultimately cell death (9)(10)(11). Remarkably, all these suppressive variants were found to have incorporated one of three mt tRNAs (tRNA Trp , tRNA Gly or tRNA Val ) or a tRNA-like sequence (TRL-64 or TRL-78) at the position corresponding to the 5′-end of the major plasmid transcript (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of an unusual tRNA-like sequence found inserted in a Neurospora retroplasmid

Mohr¹,

Wanner²,

Bertrand³

et al. 2000

Nucleic Acids Research

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We characterized an unusual tRNA-like sequence that had been found inserted in suppressive variants of the mitochondrial retroplasmid of Neurospora intermedia strain Varkud. We previously identified two forms of the tRNA-like sequence, one of 64 nt (TRL-64) and the other of 78 nt (TRL-78) containing a 14-nt internal insertion in the anticodon stem at a position expected for a nuclear tRNA intron. Here, we show that TRL-78 is encoded in Varkud mitochondrial (mt)DNA within a 7 kb sequence that is not present in Neurospora crassa wild-type 74A mtDNA. This 7-kb insertion also contains a perfectly duplicated tRNA Trp gene, segments of several mitochondrial plasmids and numerous GC-rich palindromic sequences that are repeated elsewhere in the mtDNA. The mtDNA-encoded copy of TRL-78 is transcribed and apparently undergoes 5′-and 3′-end processing and 3′ nucleotide addition by tRNA nucleotidyl transferase to yield a discrete tRNA-sized molecule. However, the 14 nt intron-like sequence in TRL-78, which is missing in the TRL-64 form, is not spliced detectably in vivo or in vitro. Our results show that TRL-78 is an unusual tRNA-like species that could be incorporated into suppressive retroplasmids by the same reverse transcription mechanism used to incorporate mt tRNAs. The tRNA-like sequence may have been derived from an intron-containing nuclear tRNA gene or it may serve some function, like tmRNA. Our results suggest that mt tRNAs or tRNA-like species may be integrated into mtDNA via reverse transcription, analogous to SINE elements in animal cells.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Neurospora Strains and Growth Conditionsmentioning

confidence: 99%

“…3720). Senescent mutant V1-2 was described previously (9). A collection of wild-type strains and natural isolates that was surveyed for the TRL sequence is Figure 1.…”

Section: Neurospora Strains and Growth Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Characterization of an unusual tRNA-like sequence found inserted in a Neurospora retroplasmid

Mohr¹,

Wanner²,

Bertrand³

et al. 2000

Nucleic Acids Research

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Genes encoding a subunit of respiratory NADH dehydrogenase (ND1) and a reverse transcriptase-like protein (RTL) are linked to ribosomal RNA gene pieces in Chlamydomonas reinhardtii mitochondrial DNA.

Boer

Gray

1988

The EMBO Journal

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Two long and uninterrupted reading frames, specifying the ND1 and RTL genes, are embedded within fragmented rRNA genes in the 15.8‐kb mitochondrial genome of Chlamydomonas reinhardtii, a unicellular green alga. The ND1 gene encodes a subunit of respiratory NADH dehydrogenase, a standard mitochondrial gene, while the RTL gene is related to the reverse transcriptase‐like part of some optional introns and plasmids in fungal mitochondria. The universal genetic code is used in both the ND1 and RTL genes; however, the latter is distinguished from the other protein coding genes of C. reinhardtii mtDNA by several characteristics which suggest that RTL may be a more recently acquired gene. Flanking each of the protein coding genes, whose mRNAs are of similar abundance, are some of the ‘scrambled’ rRNA gene pieces that are a unique feature of C. reinhardtii mtDNA. These sub‐genic modules give rise to high‐abundance, small‐sized pieces of rRNA, which are not spliced in this genetic system. Judging by the observed juxtaposition of transcripts as they hybridize to the genome, the mature rRNA and mRNA species from this region appear to be generated by precise endonucleolytic cleavages of a long RNA precursor. We suggest a model, involving reverse transcription of rRNAs and insertion of the resulting cDNAs into the mitochondrial genome, that might account for the pattern of dispersed rRNA gene pieces in C. reinhardtii mitochondrial DNA.

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In vitro replication of mitochondrial plasmid mp1 from the higher plant Chenopodium album (L.): a remnant of bacterial rolling circle and conjugative plasmids?

Backert

Kunnimalaiyaan

Börner

et al. 1998

Journal of Molecular Biology

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Mitochondrial plasmids of neurospora: Integration into mitochondrial DNA and evidence for reverse transcription in mitochondria

Cited by 128 publications

References 34 publications

Characterization of an unusual tRNA-like sequence found inserted in a Neurospora retroplasmid

Characterization of an unusual tRNA-like sequence found inserted in a Neurospora retroplasmid

Genes encoding a subunit of respiratory NADH dehydrogenase (ND1) and a reverse transcriptase-like protein (RTL) are linked to ribosomal RNA gene pieces in Chlamydomonas reinhardtii mitochondrial DNA.

In vitro replication of mitochondrial plasmid mp1 from the higher plant Chenopodium album (L.): a remnant of bacterial rolling circle and conjugative plasmids?

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