Cauliflower RNA polymerase: Partial purification and preliminary characterization of DNA-dependent enzymes

Amatoxins, phallotoxins, phallolysin, and antamanide: the biologically active components of poisonous Amanita mushrooms

This review gives a comprehensive account of the molecular toxicology of the bicyclic peptides obtained from the poisonous mushrooms of the genus Amanita. The discussion of the biochemical events will be preceded by a consideration of the chemistry of the toxic peptides. The structural features essential for biological activities of both the amatoxins and the phallotoxins will be discussed, also including the most important analytical data. Similar consideration will be given to antamanide, a cyclic peptide, which counteracts phalloidin. In addition, the phallolysins, three cytolytic proteins from Amanita phalloides will be discussed. The report on the biological activity of the amatoxins will deal with the sensitivity of the different RNA-polymerases towards the toxins and with their action on various cell types. Consideration will also be given to systems in which alpha-amanitin was used and can be used as a molecular tool; in the past, many investigators used the inhibitor in molecular biology, genetics, and even in physiological research. As for the phallotoxins, discussion of the affinity of these toxins for actin is provied. Further discussion attempts to understand the course of intoxication by filling in the gap between the first molecular event, formation of microfilaments, and the various lesions in hepatocytes during the intoxication.

Large-scale purification and subunit structure of DNA-dependent RNA polymerase II from cauliflower inflorescence

DNA-dependent RNA polymerase II (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) from cauliflower inflorescence (Brassica oleracae, var. botrytis) was highly purified by polyethyleneimine treatment on a large scale. The solubilized enzyme was partially purified by polyethyleneimine fractionation and subjected to chromatography on DEAE-Sephadex and phosphocellulose, and subsequently to sedimentation in a glycerol gradient. The specific activity (231 nmol/mg per 10 min) of this enzyme was comparable to that reported for other purified eukaryotic RNA polymerases. Analysis of the purified RNA polymerase II by polyacrylamide gel electrophoresis under nondenaturing conditions revealed a single band. The subunit composition of the enzyme was analyzed by electrophoresis under denaturing conditions. The RNA polymerase II contained subunits with molecular weights and molar ratios (in parentheses) of 180 000(1), 130 000(2), 48 000(2), 25 000(4), and 19 500(4).