title: alpha-Amanitin-resistant RNA polymerase II from carpophores of Amanita species accumulating amatoxins.
abstract: DNA-dependent RNA polymerase activities have been partially purified from carpophores of the amanitin (amatoxin)-accumulating species Amanita hygroscopica and Amanita suballiacea and the non-accumulating species Amanita brunnescens and Amanita alliacea. RNA polymerase II activities purified by ion-exchange chromatography were characterized with respect to ionic strength, template, and divalent metal ion requirements and sensitivities to inhibition by alpha-amanitin. The Ki values of alpha-amanitin for RNA polymerase II activities were: 2.0 . 10(-3) M for A. hygroscopica; 3.3 . 10(-3) M for A. suballiacea; 9.8 . 10(-6) M for A. brunnescens; 10.0 . 10(-6) M for A. alliacea. Further purification with DNA affinity chromatography of activities from A. suballiacea and A. brunnescens did not alter the apparent dissociation constants of alpha-amanitin from either enzyme. The correlation between amanitin sensitivity of RNA polymerase II and the quantity of amatoxins found in carpophores suggests these peptides may play a role in regulating transcription of messenger RNA during carpophore development.
mesh_terms: D000363:Agaricales / Q000201:enzymology*; D000545:Amanita / Q000201:enzymology*; D000546:Amanitins / Q000494:pharmacology*; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D012321:DNA-Directed RNA Polymerases / Q000302:isolation & purification*; D012318:RNA Polymerase I / Q000378:metabolism; D012319:RNA Polymerase II / Q000037:antagonists & inhibitors / Q000302:isolation & purification*
chemical_list: D000546:Amanitins; D012319:RNA Polymerase II; D012321:DNA-Directed RNA Polymerases; D012318:RNA Polymerase I