Molecular characterization of the largest subunit of Plasmodium falciparum RNA polymerase I

Mol Biochem Parasitol. 1993 Sep;61(1):37-48. doi: 10.1016/0166-6851(93)90156-r.


Plasmodium species possess developmentally regulated ribosomal RNA (rRNA) genes. This report describes the expression and gene structure of the largest subunit of P. falciparum RNA polymerase I (RNAPI), which is responsible for the synthesis of rRNA. The RNAPI largest subunit gene was present as a single copy gene on chromosome 9. Three exons encode the 2910-amino acid RNAPI polypeptide (340 140 Da). A comparison of Plasmodium, Trypanosoma, and Saccharomyces cerevisiae nuclear RNAP largest subunits identified conserved amino acid positions and class-specific amino acid positions. Novel amino acid insertions were found between RNAPI conserved regions A and B (region A'), D and DE1 (region D'), DE2 and E (region DE2'), and F and G (region F'). Leucine zipper domains were found within regions D', DE2, and DE2'. A novel serine-rich repeat domain, a domain with homology to the C-terminal domain of eukaryotic upstream binding factor (UBF), and 4 highly conserved casein kinase II (CKII) Ser/Thr phosphorylation motifs were found within a 127-amino acid sub-region of enlarged region F'. The novel RNAPI serine-rich repeat contained a conserved motif, Ser-X3-Ser, which was also identified in the serine-rich repeat domains of the P. falciparum RNAPII and RNAPIII largest subunits, as well as within a highly homologous serine-rich repeat from trophozoite antigen R45. The results of this molecular analysis indicate that phosphorylation and dephosphorylation mechanisms regulate the activity of P. falciparum RNAPI.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Blotting, Northern
  • Chromosome Mapping
  • Cloning, Molecular
  • DNA, Protozoan
  • Electrophoresis, Gel, Pulsed-Field
  • Exons
  • Humans
  • Introns
  • Molecular Sequence Data
  • Plasmodium falciparum / enzymology*
  • RNA Polymerase I / metabolism*
  • Restriction Mapping
  • Sequence Homology, Amino Acid


  • DNA, Protozoan
  • RNA Polymerase I

Associated data

  • GENBANK/L11172