Active site labeling of the RNA polymerases A, B, and C from yeast.
RNA polymerases A, B, and C from yeast were modified by reaction with 4-formylphenyl-gamma-ester of ATP as priming nucleotide followed by reduction with NaBH4. Upon phosphodiester bond formation with [alpha-32P]UTP, only the second largest subunit, A135, B150, or C128, was labeled in a template-dependent reaction. This indicates that these polypeptide chains are functionally homologous. The product covalently bound to B150 subunit was found to consist of a mixture of ApU and a trinucleotide. Enzyme labeling exhibited the characteristic alpha-amanitin sensitivity reported for A and B RNA polymerases. Labeling of both large subunits of enzyme A and B but not of any of the smaller subunits was observed when the reduction step stabilizing the binding of the priming nucleotide was carried out after limited chain elongation. These results illustrate the conservative evolution of the active site of eukaryotic RNA polymerases.
Riva
M
M
Service de Biochimie, Centre d'Etudes Nucléaires de Saclay, Gif-sur-Yvette, France.
Schäffner
A R
AR
Sentenac
A
A
Hartmann
G R
GR
Mustaev
A A
AA
Zaychikov
E F
EF
Grachev
M A
MA
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000345:Affinity Labels; D000546:Amanitins / Q000494:pharmacology; D001665:Binding Sites; D012321:DNA-Directed RNA Polymerases / Q000032:analysis*; D009841:Oligonucleotides / Q000032:analysis; D012318:RNA Polymerase I / Q000032:analysis*; D012319:RNA Polymerase II / Q000032:analysis*; D012320:RNA Polymerase III / Q000032:analysis*; D015003:Yeasts / Q000201:enzymology*
D000345:Affinity Labels; D000546:Amanitins; D009841:Oligonucleotides; D000255:Adenosine Triphosphate; D012319:RNA Polymerase II; D012321:DNA-Directed RNA Polymerases; D012318:RNA Polymerase I; D012320:RNA Polymerase III