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Both open reading frames of the linear plasmid pMC3-2 from the ascomycete Morchella conica are transcribed in vivo
1Institut für Mikrobiologie, Westflische Wilhelms-Universität, Münster, Federal Republic of Germany.
Abstract:
Mitochondrial RNA was isolated from the morel strain Morchella conica 3 harbouring the linear plasmid pMC3-2 and subjected to gel electrophoresis followed by a Northern analysis using cloned fragments of the plasmid pMC3-2 as probes. Hybridization was obtained only with central parts of pMC3-2 and specific bands of mtRNA. The hybridization bands (2.8 kb and 1.0 kb) correspond in size to the length of the two ORFs of pMC3-2 which were deduced from nucleotide-sequence data. Thus, both ORFs, one encoding a DNA polymerase and the other a yet unknown protein, are transcribed in the mitochondria of the plasmid-bearing Morchella conica strain.
Insights
Researchers studied mitochondrial RNA in the Morchella conica fungus. They found that the linear plasmid pMC3-2, which contains genes for DNA polymerase, is actively transcribed within the mitochondria.
Area of Science:
- Mycology
- Molecular Biology
- Genetics
Background:
- Mitochondrial RNA (mtRNA) plays a crucial role in cellular respiration and gene expression within mitochondria.
- The presence and function of linear plasmids in fungal mitochondria, such as pMC3-2 in Morchella conica, are not fully understood.
- Understanding the transcription of plasmid-borne genes is essential for elucidating their impact on host cell biology.
Purpose of the Study:
- To investigate the transcription of the linear plasmid pMC3-2 in the mitochondrial genome of the morel strain Morchella conica 3.
- To identify which open reading frames (ORFs) on the plasmid are transcribed into mtRNA.
- To determine the size and characteristics of the transcribed mtRNA molecules.
Main Methods:
- Isolation of mitochondrial RNA from Morchella conica strain 3.
- Gel electrophoresis to separate mtRNA molecules.
- Northern blot analysis using cloned fragments of the pMC3-2 plasmid as hybridization probes.
Main Results:
- Specific hybridization was observed between central fragments of the pMC3-2 plasmid and distinct mtRNA bands.
- Two hybridization bands of 2.8 kb and 1.0 kb were detected, corresponding to the sizes of the two ORFs on pMC3-2.
- These results indicate that both ORFs, including the one encoding DNA polymerase, are transcribed in the mitochondria.
Conclusions:
- The linear plasmid pMC3-2 is transcriptionally active within the mitochondria of Morchella conica.
- Both identified ORFs on the plasmid, one for DNA polymerase and another for an unknown protein, are expressed as mtRNA.
- This study provides evidence for the expression of plasmid-encoded genes in fungal mitochondria, contributing to our understanding of mitochondrial genetics.