Mushroom Amanita phalloides

Phalloidin and phallacidin are cyclic peptides from the mushroom Amanita phalloides that stabilize F-actin. Phalloidin binds to residues 114-118 of an actin protomere and blocks nucleotide exchange without interfering with nucleotide hydrolysis. It enhances the rate of nucleation as well as that of elongation. It slowly penetrates the cell membrane and is used for immunocytochemical localization of F-actin. 

Ingestion of as little as 3 g of the death cap mushroom Amanita phalloides may constitute a lethal dose for some people. 

The mushroom Amanita phalloides has evolved a very effective defense mechanism against predators. It produces a-amanitin, which disrupts mRNA formation in animal cells by blocking Pol II and, at higher concentrations, Pol III. Neither Pol I nor bacterial RNA polymerase is sensitive to a-amanitin—nor is the RNA polymerase II of A. phalloides itself ... 

Pattern of serum alanine aminotransferase (ALT) and bilirubin in the plasma, following poisoning with the toxic mushroom Amanita phalloides. 

The poisonous components of the most deadly mushroom Amanita phalloides (the Death Cap) are bicyclic heptapeptides which have an additional covalent bond that connects the ( -sulfur atom of an l-cysteine residue with the carbon atom in position 2 of the indole ring of the L-tryptophan. Phalloidin (or phalloidine) is the most abundant member of a whole family of related cyclic heptapeptides called phallotoxins (for a review, see Wieland1 1). These poisonous peptides, therefore, contain a cross-linking moiety consisting of L-tryptophan coupled to L-cysteine, designated tryptathionine (1), alternatively called 5-(trypto-phan-2-yl)cysteine or 2-(L-3-alanylsulfenyl)-L-tryptophan (Scheme 1). 

The most useful inhibitor of eukaryotic transcription has been a-amanitin, a major toxic substance in the poisonous mushroom Amanita phalloides. The toxin preferentially binds to and inhibits RNA polymerase II (see table 28.4). At high concentrations it also can inhibit RNA polymerase III but not RNA polymerase I or bacterial, mitochondrial, or chloroplast RNA polymerases. 

No. Eukaryotic RNA polymerases have been isolated from many tissues, and in all cases, three distinct enzymes have been found in the nucleus. All contain a number of polypeptide subunits and are complex in structure, RNA polymerase I is known to be involved specifically in the transcription of rRNA genes. RNA polymerase II gives rise to transcripts that are subsequently processed to yield mRNA. RNA polymerase 111 is responsible for the transcription of the tRNA genes and a small ribosomal RNA gene that yields a species called 55 RNA. The three polymerases are distinguishable from one another by their differential sensitivity to the drug a-amanitin (the toxic principle of the mushroom Amanita phalloides), which does not affect bacterial RNA polymerase. RNA polymerase... 

Cytochalasins, drugs that inhibit cellular processes that require actin polymerization and depolymerization (e.g., phagocytosis, cytokinesis, clot retraction, etc.), also act by severing and capping actin filaments. Actin filaments can be stabilized by phalloidin, derived from the poisonous mushroom Amanita phalloides. Assembly of actin filaments into bundles (as in microvilli) and three-dimensional networks is accomplished by two groups of cross-linking proteins (Table 21-6). 

Mushrooms Amanita phalloides type) Severe nausea and vomiting 8 hours after ingestion delayed hepatic and renal failure... 

Muscarine from the mushroom. Amanita muse aria, has become a valuable biochemical tool for measuring peripheral effects on cholinergic receptors (see Volume 23 of this series). Each year Phalloidin from the mushroom. Amanita phalloides, causes several deaths in Europe from mushroom poisoning and has been the subject of a book by Theodor Wieland. In this volume, the subjects of alkaloids and mushrooms are brought together in a paper written by a team of experts from Poland in Alkaloids from Mushrooms. ... 

The extremely poisonous green mushroom Amanita phalloides contains a number of cyclic peptides classified as phallotoxins (heptapeptides), ama-toxins (octapeptides), and a decapeptide antagonist called antamanide (Wieland and Wieland, 1972). Crystal structure analyses have been completed on jS-amanitin, on antamanide, and on a biologically active analog, both com-plexed and uncomplexed. 

RNA polymerase II is inhibited by a-amanitin, the toxin of the death cap mushroom (Amanita phalloides), which, if eaten, can be fatal. 

A cyclic peptide that neutralizes the effect of phalline B, a toxin (also a cyclic peptide) present in the deadly mushroom Amanita phalloides. 

Natural products, including herbal products derived from naturcd products, are exempt from regulation as food additives by the FDA because the chemiccds they contain occur naturally and have not been added by people. However, the majority of toxic chemicals we eat (including many that can cause cancer) occur naturally in our food. In fact, many toxic natural products are much more potent than any of the food additives that have ever been used. Yet media coverage of chemicals in food usually focuses on chemicals that have been added to food. The natural chemicals present in foods often only make the news when an accidental poisoning has occurred, such as when someone dies from eating deathcap mushrooms (Amanita phalloides. ... 

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