Journal
BIOPOLYMERS
Volume 94, Issue 5, Pages 659-664Publisher
JOHN WILEY & SONS INC
DOI: 10.1002/bip.21416
Keywords
amanitin; phalloidin; phallacidin; prolyl oligopeptidase; Conocybe; Amanita
Categories
Funding
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [R01GM088274] Funding Source: NIH RePORTER
- NIGMS NIH HHS [R01 GM088274] Funding Source: Medline
Ask authors/readers for more resources
Some species of mushrooms in the genus Amanita are extremely poisonous and frequently fatal to mammals including humans and dogs. Their extreme toxicity is due to amatoxins such as alpha- and beta-amanitin. Amanita mushrooms also biosynthesize a chemically related group of toxins, the phallotoxins, such as phalloidin. The amatoxins and phallotoxins (collectively known as the Amanita toxins) are bicyclic octa- and heptapeptides, respectively. Both contain an unusual Trp-Cys cross-bridge known as tryptathionine. We have shown that, in Amanita bisporigera, the amatoxins and phallotoxins are synthesized as proproteins on ribosomes and not by nonribosomal peptide synthetases. The proproteins are 34-35 amino acids in length and have no predicted signal peptides. The genes for a-amanitin (AMA1) and phallacidin (PHA1) are members of a large family of related genes, characterized by highly conserved amino acid sequences flanking a hypervariable toxin region. The toxin regions are flanked by invariant proline (Pro) residues. An enzyme that could cleave the proprotein of phalloidin was purified from the phalloidin-producing lawn mushroom Conocybe apala. The enzyme is a serine protease in the prolyl oligopeptidase (POP) subfamily. The same enzyme cuts at both Pro residues to release the linear hepta- or octapeptide. (c) 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 94: 659-664, 2010.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available