Identification and characterization of a Plasmodium falciparum RNA polymerase gene with similarity to mitochondrial RNA polymerases.
Nearly all mitochondrial RNA polymerase genes identified to date are encoded in the nucleus and have similarities to T3 and T7 bacteriophage RNA polymerases. Some chloroplast genes are also transcribed by T3/T7 phage-like RNA polymerases, raising the possibility that the apicomplexan parasites, which have both a mitochondrion and a plastid, might have two such genes. As part of an investigation of Plasmodium falciparum organelle transcription, we initiated a search for T3/T7 bacteriophage-like RNA polymerase genes. We employed degenerate primers based on highly conserved plant, animal and fungal mitochondrial RNA polymerase sequences to amplify corresponding P. falciparum sequences by polymerase chain reaction (PCR). Less well-conserved flanking sequences were obtained by inverse PCR. The resulting sequence predicts a 1503 amino acid open reading frame with similarity to other T3/T7 phage-like RNA polymerases. Essential amino acids that have been identified in T7 mutant analyses are conserved in the P. falciparum RNA polymerase gene. Comparison of the sequence with preliminary data from the P. falciparum genome sequencing project revealed strain heterogeneity within two regions of the gene. The amino-terminal predicted amino acid sequence of the RNA polymerase gene has similarities to mitochondrial targeting sequences. Taken together, these points suggest that we have identified the P. falciparum mitochondrial RNA polymerase gene.
Li
J
J
Department of Pathobiology, School of Public Health and Community Medicine, University of Washington, Seattle 98195, USA.
Maga
J A
JA
Cermakian
N
N
Cedergren
R
R
Feagin
J E
JE
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017125:Genes, Protozoan; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D014764:Viral Proteins
D014764:Viral Proteins; C081591:bacteriophage T3 RNA polymerase; C062210:bacteriophage T7 RNA polymerase; D012321:DNA-Directed RNA Polymerases