Alpha-Sarcin
| α-Sarcin ( Aspergillus giganteus ) | ||
|---|---|---|
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| NMR band model of alpha-sarcin, according to PDB 1DE3 | ||
| Mass / length primary structure | 150 amino acids | |
| Identifier | ||
| Gene name (s) | sar | |
| External IDs | ||
| Enzyme classification | ||
| EC, category | 3.1.27.10 , esterase | |
| Response type | Cleavage of phosphodiester bonds | |
| Substrate | rRNA + H 2 O | |
| Products | defective rRNA pieces | |
α-Sarcin is a lectin from the Aspergillus giganteus mold . It is one of the few high-molecular protein toxins from the group of mycotoxins .
Mode of action
α-Sarcin inhibits eukaryotic protein biosynthesis by blocking the binding of aminoacyl- tRNA to the ribosomes . It acts as a ribonuclease , which means that it separates the strand of nucleotides of the 28 S - rRNA by cleaving a phosphodiester bond . About 400 nucleotides are released. In a remarkable way, this takes place in the immediate vicinity of the site of action of ricin or Shiga toxin , which function as RNA- N glycosidases . Another distinguishing feature between these lectins is the molecular mass of the active subunits, which in the case of α-sarcin at approx. 17 kDa is significantly lower than the corresponding subunits of ricin with approx. 30 kDa.
Similar toxins
The very similar lectins restrictocin and mitogillin from the Aspergillus restrictus mold also inhibit eukaryotic protein synthesis.
literature
- EJ Ackerman, SK Saxena, N. Ulbrich: α-Sarcin causes a specific cut in 28S rRNA when microinjected into Xenopus oocytes. In: J. Biol. Chem. 263, 1988, pp. 17076-17083. PMID 3182833
- Luen Hwua, Kuan-Chun Huangb, Dow-Tien Chenb, Alan Linb: The Action Mode of the Ribosome-Inactivating Protein α-Sarcin. In: J. Biomedical. Science. 7, 2000, pp. 420-428. PMID 10971140