title: Mitochondrial and chloroplast phage-type RNA polymerases in Arabidopsis.
abstract: In addition to the RNA polymerases (RNAPs) transcribing the nuclear genes, eukaryotic cells also require RNAPs to transcribe the genes of the mitochondrial genome and, in plants, of the chloroplast genome. The plant Arabidopsis thaliana was found to contain two nuclear genes similar to genes encoding the mitochondrial RNAP from yeast and RNAPs of bacteriophages T7, T3, and SP6. The putative transit peptides of the two polymerases were capable of targeting fusion proteins to mitochondria and chloroplasts, respectively, in vitro. The results indicate that the mitochondrial RNAP in plants is a bacteriophage-type enzyme. A gene duplication event may have generated the second RNAP, which along with the plastid-encoded eubacteria-like RNAP could transcribe the chloroplast genome.
authors.affiliation: Humboldt University Berlin, Institute of Biology, Chausseestrasse 117, D-10115 Berlin, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Hedtke
authors.forename: T
authors.initials: T
authors.lastname: Börner
authors.forename: A
authors.initials: A
authors.lastname: Weihe
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics; D002736:Chloroplasts / Q000201:enzymology*; D003001:Cloning, Molecular; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics*; D005091:Exons; D017343:Genes, Plant; D007438:Introns; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013604:T-Phages / Q000201:enzymology
chemical_list: D011993:Recombinant Fusion Proteins; C070852:RNA polymerase SP6; D012321:DNA-Directed RNA Polymerases