Substoichiometric shifting in the plant mitochondrial genome is influenced by a gene homologous to MutS

Authors

Ricardo V. Abdelnoor, University of Nebraska - Lincoln
Ryan Yule, University of Nebraska - Lincoln
Annakaisa Elo, University of Nebraska - Lincoln
Alan C. Christensen, University of Nebraska - LincolnFollow
Gilbert Meyer-Gauen, University of Nebraska - Lincoln
Sally A. MacKenzie, University of Nebraska-LincolnFollow

Date of this Version

5-2003

Comments

Published in Proceedings of the National Academy of Sciences USA 100:10 (May 13, 2003), pp. 5968-5973; doi: 10.1073/pnas.1037651100. Copyright 2003 National Academy of Sciences USA. Used by permission.

Abstract

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.