Cloning and characterization of a cDNA encoding a bacteriophage-type RNA polymerase from the higher plant Chenopodium album

Nucleic Acids Res. 1997 Jun 15;25(12):2319-25. doi: 10.1093/nar/25.12.2319.


We have cloned a full-length cDNA from the higher plant Chenopodium album coding for a single subunit bacteriophage-type RNA polymerase. The cDNA isolated from an actively growing cell suspension culture recognized a 3.8 kb transcript on Northern blots. The open reading frame comprises 987 amino acids with a predicted molecular mass of 112 kDa. A comparison of the protein sequence with those of the two known fungal mitochondrial RNA polymerases, from Saccharomyces cerevisiae and Neurospora crassa , reveals extensive homology between the three enzymes. with complete conservation of all catalytically essential amino acids. The putative mitochondrial RNA polymerase from C.album , as well as homologous sequences from rice and barley, which have been partially cloned, lack two catalytically non-essential regions of up to 176 amino acids near the C-terminus present in the two fungal mitochondrial RNA polymerases. The extreme N-terminus of the cloned C.album RNA polymerase displays features of a potential mitochondrial transit sequence. In phylogenetic trees constructed to compare the evolutionary relationships between the different single subunit RNA polymerases the C.album sequence forms a subgroup together with the S.cerevisiae and the N.crassa mitochondrial RNA polymerases, well separating from both bacteriophage enzymes and plasmid-encoded RNA polymerases found in mitochondria of many fungi and some higher plants.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacteriophages / enzymology*
  • Base Sequence
  • Cells, Cultured
  • Cloning, Molecular
  • Conserved Sequence
  • DNA Primers
  • DNA, Complementary
  • DNA-Directed RNA Polymerases / biosynthesis*
  • DNA-Directed RNA Polymerases / chemistry*
  • Evolution, Molecular
  • Mitochondria / enzymology
  • Molecular Sequence Data
  • Molecular Weight
  • Neurospora crassa / enzymology
  • Phylogeny
  • Plants / enzymology*
  • Polymerase Chain Reaction
  • RNA / biosynthesis
  • RNA, Mitochondrial
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Saccharomyces cerevisiae / enzymology
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Transcription, Genetic


  • DNA Primers
  • DNA, Complementary
  • RNA, Mitochondrial
  • Recombinant Proteins
  • RNA
  • DNA-Directed RNA Polymerases

Associated data

  • GENBANK/Y08067
  • GENBANK/Y11599
  • GENBANK/Y11600