RNA polymerases B and C are more closely related to each other than to RNA polymerase A.
Amino acid sequence comparison of the largest subunit of the three forms of yeast nuclear RNA polymerase disclosed six major conserved regions that are partly retained in the cognate subunits from bacteria, viral, and insect enzymes (Mémet, S., Gouy, M., Marck, C., Sentenac, A., and Buhler, J.-M. (1988) J. Biol. Chem. 263, 2830-2839). Within these conserved domains, the high sequence similarity of B220 and C160 subunits (52% identity) sets them apart from yeast enzyme A subunit A190. Parsimony analysis at the gene and protein levels suggests the existence of a transient ancestor to eukaryotic RNA polymerases B and C. These results are discussed in the light of the recent finding of class C genes containing RNA polymerase B promoter elements.
Mémet
S
S
Service de Biochimie, Centre d'Etudes, Nucléaires de Saclay, Gif-sur-Yvette, France.
Saurin
W
W
Sentenac
A
A
D000595:Amino Acid Sequence; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010802:Phylogeny; D012318:RNA Polymerase I / Q000235:genetics*; D012319:RNA Polymerase II / Q000235:genetics*; D012320:RNA Polymerase III / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
D046911:Macromolecular Substances; D012319:RNA Polymerase II; D012321:DNA-Directed RNA Polymerases; D012318:RNA Polymerase I; D012320:RNA Polymerase III