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Variant mitochondrial plasmids of broad bean arose by recombination and are controlled by the nuclear genome.

ABSTRACT: Various cytoplasms of broad bean contain three mitochondrial plasmids (mtp1, 2 and 3), previously described. In cytoplasm 350 we have observed several additional mitochondrial plasmids, varying in number and in identity according to the nuclear background. Replacement of the nucleus by backcrossing led to the appearance or disappearance of additional plasmids, indicating that the nuclear genome controls either the creation or the copy level of mitochondrial plasmids. Analysis of eight variant additional plasmids (mtp4-11) suggests that they all result from a double recombination event between mtp1 and mtp2. In all cases, one recombination point was located within a 276-bp sequence, identical in both plasmids. For 7 plasmids, the region in which the second recombination event occurred could be narrowed down to a short stretch containing imperfect tandem repeats of a 31-bp motif. The largest sequence shared by the recombination regions was hexanucleotide GCGACG.

SUBMITTER: Flamand MC

PROVIDER: S-EPMC310587 | biostudies-other | 1993 Nov

REPOSITORIES: biostudies-other

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Variant mitochondrial plasmids of broad bean arose by recombination and are controlled by the nuclear genome.

Flamand M C MC Duc G G Goblet J P JP Hong L L Louis O O Briquet M M Boutry M M

Nucleic acids research 19931101 23

Various cytoplasms of broad bean contain three mitochondrial plasmids (mtp1, 2 and 3), previously described. In cytoplasm 350 we have observed several additional mitochondrial plasmids, varying in number and in identity according to the nuclear background. Replacement of the nucleus by backcrossing led to the appearance or disappearance of additional plasmids, indicating that the nuclear genome controls either the creation or the copy level of mitochondrial plasmids. Analysis of eight variant ad ...[more]

PMID: 8265364

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Project description:In eukaryotic cells, the production of cellular energy requires close interplay between nuclear and mitochondrial genomes. The mitochondrial genome is essential in that it encodes several genes involved in oxidative phosphorylation. Each cell contains several mitochondrial genome copies and mitochondrial DNA recombination is a widespread process occurring in plants, fungi, protists, and invertebrates. Saccharomyces cerevisiae has proved to be an excellent model to dissect mitochondrial biology. Several studies have focused on DNA recombination in this organelle, yet mostly relied on reporter genes or artificial systems. However, no complete mitochondrial recombination map has been released for any eukaryote so far. In the present work, we sequenced pools of diploids originating from a cross between two different S. cerevisiae strains to detect recombination events. This strategy allowed us to generate the first genome-wide map of recombination for yeast mitochondrial DNA. We demonstrated that recombination events are enriched in specific hotspots preferentially localized in non-protein-coding regions. Additionally, comparison of the recombination profiles of two different crosses showed that the genetic background affects hotspot localization and recombination rates. Finally, to gain insights into the mechanisms involved in mitochondrial recombination, we assessed the impact of individual depletion of four genes previously associated with this process. Deletion of NTG1 and MGT1 did not substantially influence the recombination landscape, alluding to the potential presence of additional regulatory factors. Our findings also revealed the loss of large mitochondrial DNA regions in the absence of MHR1, suggesting a pivotal role for Mhr1 in mitochondrial genome maintenance during mating. This study provides a comprehensive overview of mitochondrial DNA recombination in yeast and thus paves the way for future mechanistic studies of mitochondrial recombination and genome maintenance.

Dataset Information

Variant mitochondrial plasmids of broad bean arose by recombination and are controlled by the nuclear genome.

Publications

Variant mitochondrial plasmids of broad bean arose by recombination and are controlled by the nuclear genome.

Similar Datasets

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