title: Coexistence of nuclear DNA-encoded tRNAVal(AAC) and mitochondrial DNA-encoded tRNAVal(UAC) in mitochondria of a liverwort Marchantia polymorpha.
abstract: The liverwort Marchantia polymorpha mitochondrial DNA encodes almost all tRNAs required for mitochondrial translation except for the isoleucine (AUU, AUC) and threonine (ACA, ACG) codons, while the missing tRNAs are supplied in part by the nucleus and imported in mitochondria. In this paper, we report a finding of two radically different nuclear tRNAVal(AAC) genes and import of the corresponding tRNA isoacceptors in M.polymorpha mitochondria. This finding is surprising since the mtDNA encodes the gene for tRNAVal(UAC), which alone was considered sufficient for translating all four valine codons GUN by the U/N wobble mechanism. The present results suggest for the first time that the import of ncDNA-encoded tRNAs may result in decoding overlaps in plant mitochondria. The coexistence of nuclear DNA-encoded tRNAVal(AAC) and mitochondrial DNA-encoded tRNAVal(UAC) in liverwort mitochondria and the significance for the decoding mechanism as well as evolution of tRNA import are discussed.
authors.affiliation: Laboratory of Plant Molecular Biology, Division of Applied Life Science, The Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Akashi
authors.forename: M
authors.initials: M
authors.lastname: Takenaka
authors.forename: S
authors.initials: S
authors.lastname: Yamaoka
authors.forename: Y
authors.initials: Y
authors.lastname: Suyama
authors.forename: H
authors.initials: H
authors.lastname: Fukuzawa
authors.forename: K
authors.initials: K
authors.lastname: Ohyama
mesh_terms: D001692:Biological Transport; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000235:genetics* / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics* / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics* / Q000378:metabolism; D017343:Genes, Plant; D012366:RNA, Transfer, Val / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial; D018744:DNA, Plant; D012366:RNA, Transfer, Val