title: Identification and characterization of two phage-type RNA polymerase cDNAs in the moss Physcomitrella patens: implication of recent evolution of nuclear-encoded RNA polymerase of plastids in plants.
abstract: We isolated two cDNAs for the genes PpRPOT1 and PpRPOT2 that encode phage-type RNA polymerases (RPOTs) from Physcomitrella patens. Transcriptional activity of the encoded proteins was demonstrated by an in vitro transcription assay. Transiently expressed RPOT green fluorescent protein fusion proteins were both targeted to mitochondria. These results suggest that both PpRPOT1 and PpRPOT2 proteins function as mitochondrial RNA polymerases. Detailed phylogenetic analysis using neighbor-joining and maximum-likelihood methods with both DNA and protein sequences indicated that the two genes of P. patens form a sister group to all flowering plant genes. This suggests that the gene duplication leading to the production of plastid-type isozymes occurred after the separation of vascular plant lineage from bryophyte lineage. We therefore suggest that the generation of nuclear-encoded RNA polymerase of chloroplast is a rather recent event during the evolution of land plants.
authors.affiliation: Department of Molecular Biology, Faculty of Science, Saitama University, Saitama Prefecture, 338-8570, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Kabeya
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Naoki
authors.initials: N
authors.lastname: Sato
mesh_terms: D000595:Amino Acid Sequence; D019068:Bryopsida / Q000201:enzymology* / Q000235:genetics; D002467:Cell Nucleus / Q000201:enzymology / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D012321:DNA-Directed RNA Polymerases / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D020440:Gene Duplication; D049452:Green Fluorescent Proteins; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D010944:Plants / Q000201:enzymology* / Q000235:genetics; D018087:Plastids / Q000201:enzymology* / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013604:T-Phages / Q000201:enzymology
chemical_list: D018076:DNA, Complementary; D007527:Isoenzymes; D008164:Luminescent Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D012321:DNA-Directed RNA Polymerases