Substoichiometric Shifting in the Plant Mitochondrial Genome Is Influenced by a Gene Homologous to MutS

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 100; no. 10; pp. 5968 - 5973
• Main Authors: Abdelnoor, Ricardo V., Yule, Ryan, Elo, Annakaisa, Christensen, Alan C., Meyer-Gauen, Gilbert, Mackenzie, Sally A.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 13.05.2003; National Acad Sciences; The National Academy of Sciences
• Subjects: Adenosine Triphosphatases - genetics; Amino Acid Sequence; Arabidopsis - genetics; Arabidopsis Proteins - genetics; Bacterial Proteins; Base Sequence; Biological Sciences; Chromosome Mapping; Cloning, Molecular; DNA; DNA Primers; DNA, Mitochondrial - genetics; DNA, Plant - genetics; DNA-Binding Proteins; Escherichia coli Proteins - genetics; Flowers & plants; Genes; Genetic loci; Genetic mutation; Genome, Plant; Genomes; Genomics; Kinetics; Mitochondria - genetics; Mitochondrial DNA; Molecular Sequence Data; Molecules; MutS DNA Mismatch-Binding Protein; Phenotypes; Plant cells; Plants; Polymerase Chain Reaction; Sequence Alignment; Sequence Homology, Amino Acid
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1037651100

The plant mitochondrial genome is retained in a multipartite structure that arises by a process of repeat-mediated homologous recombination. Low-frequency ectopic recombination also occurs, often producing sequence chimeras, aberrant ORFs, and novel subgenomic DNA molecules. This genomic plasticity may distinguish the plant mitochondrion from mammalian and fungal types. In plants, relative copy number of recombination-derived subgenomic DNA molecules within mitochondria is controlled by nuclear genes, and a genomic shifting process can result in their differential copy number suppression to nearly undetectable levels. We have cloned a nuclear gene that regulates mitochondrial substoichiometric shifting in Arabidopsis. The CHM gene was shown to encode a protein related to the MutS protein of Escherichia coli that is involved in mismatch repair and DNA recombination. We postulate that the process of substoichiometric shifting in plants may be a consequence of ectopic recombination suppression or replication stalling at ectopic recombination sites to effect molecule-specific copy number modulation.