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The linear plasmid pMC3-2 from Morchella conica is structurally related to adenoviruses
M Rohe1, K Schrage, F Meinhardt
1Institut für Mikrobiologie, Westfälische Wilhelms-Universität, Münster, Federal Republic of Germany.
Abstract:
pMC3-2, one of two linear plasmids localised in the mitochondria of the ascomycete Morchella conica, was completely sequenced. It is 6044 bp in size, contains terminal inverted repeats of 713 and 710 bp length and two open reading frames, ORF1 and ORF2, spanning 2706 bp and 918 bp, respectively. ORF1 probably encodes a viral B-type DNA-polymerase. Concerning ORF2, no homology to any other published protein- or DNA-sequence could be detected. According to the structure of DNA-polymerases, linear plasmids can be grouped into two classes reflecting their localisation either in the cytoplasm or within the mitochondria. In general, the structure of plasmid pMC3-2, as well as of other linear plasmids from filamentous fungi, indicates a close relationship of these genetic elements to adenoviruses.
Insights
The complete sequence of the linear mitochondrial plasmid pMC3-2 from Morchella conica was determined. This fungal plasmid shares structural similarities with adenoviruses, suggesting a potential evolutionary link.
Area of Science:
- Mycology
- Molecular Biology
- Virology
Background:
- Mitochondria of the ascomycete Morchella conica harbor two linear plasmids.
- Linear plasmids are found in various organisms, including fungi, and exhibit diverse structures and functions.
Purpose of the Study:
- To determine the complete nucleotide sequence of the linear mitochondrial plasmid pMC3-2.
- To identify potential open reading frames and analyze their homology to known sequences.
- To investigate the evolutionary relationship of pMC3-2 to other genetic elements.
Main Methods:
- Complete DNA sequencing of the pMC3-2 plasmid.
- Bioinformatic analysis to identify open reading frames (ORFs).
- Sequence homology searches against public databases.
Main Results:
- The pMC3-2 plasmid is 6044 bp long with terminal inverted repeats.
- Two open reading frames (ORFs) were identified: ORF1 (2706 bp) likely encoding a viral DNA-polymerase, and ORF2 (918 bp) with no detectable homology.
- Structural analysis suggests a relationship between pMC3-2 and adenoviruses.
Conclusions:
- The complete sequence of pMC3-2 provides insights into the genetic makeup of mitochondrial plasmids in Morchella conica.
- The presence of a putative viral DNA-polymerase suggests a potential viral origin or interaction.
- The structural similarities to adenoviruses indicate a possible evolutionary connection between fungal linear plasmids and viral genomes.