A DNA-dependent RNA synthesis by wheat-germ RNA polymerase II insensitive to the fungal toxin alpha-amanitin.
Wheat-germ RNA polymerase II is able to catalyse a DNA-dependent reaction of RNA synthesis in the presence of a high concentration (1 mg/ml) of the fungal toxin alpha-amanitin. This anomalous reaction is specifically directed by single-stranded or double-stranded homopolymer templates, such as poly(dC) or poly(dC).poly(dG), and occurs in the presence of either Mn2+ or Mg2+ as the bivalent metal cofactor. In contrast, the transcription of other synthetic templates, such as poly(dT), poly(dA).poly(dT) or poly[d(A-T)] is completely abolished in the presence of 1 microgram of alpha-amanitin/ml, in agreement with well-established biochemical properties of class II RNA polymerases. Size analysis of reaction products resulting from transcription of (dC)n templates of defined lengths suggests that polymerization of RNA chains proceeds through a slippage mechanism. The fact that alpha-amanitin does not impede this synthetic reaction implies that the amatoxin interferes with the translocation of wheat-germ RNA polymerase II along the DNA template.
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Centre de Biochimie et de Biologie Moléculaire, Centre National de la Recherche Scientifique, Marseille, France.
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D000546:Amanitins / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism*; D008956:Models, Chemical; D009693:Nucleic Acid Hybridization; D011066:Poly C / Q000235:genetics / Q000378:metabolism; D011068:Poly G / Q000235:genetics / Q000378:metabolism; D012313:RNA / Q000096:biosynthesis*; D012319:RNA Polymerase II / Q000187:drug effects / Q000378:metabolism*; D013698:Templates, Genetic; D014158:Transcription, Genetic; D014908:Triticum / Q000201:enzymology
D000546:Amanitins; D011068:Poly G; C023826:poly(dC); C026628:poly(dG); D011066:Poly C; D012313:RNA; D004247:DNA; D012319:RNA Polymerase II