Characterization of a gene encoding a single-subunit bacteriophage-type RNA polymerase from maize which is alternatively spliced

Mol Gen Genet. 1998 Oct;260(1):30-7. doi: 10.1007/s004380050867.


Single-subunit RNA polymerases belonging to the T3/T7 bacteriophage family are thought to be common throughout eukaryotes. We report the isolation and characterization of a nucleus-encoded single-subunit RNA polymerase gene from maize. This gene is highly homologous to other single-subunit RNA polymerase genes from Arabidopsis, Chenopodium. yeast and Neurospora crassa involved in organellar transcription. Genomic Southern analysis reveals 10 to 15 hybridising fragments, suggesting that maize contains a small gene family. The isolated gene contains 19 exons and its genomic structure is highly conserved when compared to the three Arabidopsis homologues. Unlike the case in Arabidopsis, intron-12 of the maize bacteriophage-type RNA polymerase gene is alternatively spliced. Quantitative RT-PCR revealed that the resultant alternatively spliced transcript represents approximately 21 to 26% of the total polymerase mRNA in maize coleoptiles. The orthologous wheat bacteriophage-type RNA polymerase is also alternatively spliced and the intron exhibits 78% identity to maize intron-12. The conservation in alternative splicing between wheat and maize and its absence from Arabidopsis suggest a functional requirement for the alternatively spliced product.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing*
  • Base Sequence
  • Chloroplasts / enzymology
  • Chloroplasts / genetics
  • Cloning, Molecular
  • Conserved Sequence
  • DNA-Directed RNA Polymerases / classification
  • DNA-Directed RNA Polymerases / genetics*
  • Genes, Plant*
  • Mitochondria / enzymology
  • Mitochondria / genetics
  • Molecular Sequence Data
  • Peptide Chain Initiation, Translational
  • Sequence Analysis, DNA
  • T-Phages / enzymology
  • T-Phages / genetics
  • Viral Proteins / genetics
  • Zea mays / enzymology
  • Zea mays / genetics*


  • Viral Proteins
  • DNA-Directed RNA Polymerases

Associated data

  • GENBANK/AJ005343
  • GENBANK/AJ005344