Silent mitochondrial and active nuclear genes for subunit 2 of cytochrome c oxidase (cox2) in soybean: evidence for RNA-mediated gene transfer.
In most plants and other eukaryotes investigated, the mitochondrial genome carries the gene encoding subunit 2 of cytochrome c oxidase (cox2). In this paper, we show that the previously reported mitochondrial cox2 of soybean is actually silent, and that there is an expressed, single-copy, nucleus-encoded cox2. Molecular cloning and sequence analysis of cox2 cDNA and genomic clones show that the soybean nuclear gene encodes an N-terminal extension that resembles a signal sequence for mitochondrial import and whose coding sequence is separated by an intron from that corresponding to mtDNA-encoded cox2. Comparison of soybean mitochondrial and nuclear cox2 sequences clearly indicates that in an ancestor of soybean, cox2 was transferred from the mitochondrion to the nucleus via a C-to-U edited RNA intermediate.
Covello
P S
PS
Canadian Institute for Advanced Research, Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia.
Gray
M W
MW
D000595:Amino Acid Sequence; D001483:Base Sequence; D002467:Cell Nucleus / Q000502:physiology*; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics*; D046911:Macromolecular Substances; D008928:Mitochondria / Q000502:physiology*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016133:Polymerase Chain Reaction; D012313:RNA / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013025:Glycine max / Q000201:enzymology* / Q000235:genetics*; D014162:Transfection
D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D012313:RNA; D004247:DNA; D003576:Electron Transport Complex IV