Читать книгу Snyder and Champness Molecular Genetics of Bacteria - Tina M. Henkin - Страница 176

Puromycin mimics the 3′ end of tRNA with an amino acid attached (aa-tRNA). It enters the ribosome as does an aa-tRNA, and the peptidyltransferase attaches it to the growing polypeptide. However, it does not translocate properly from the A site to the P site, and the peptide with puromycin attached to its carboxyl terminus is released from the ribosome, terminating translation.

Studies with puromycin have contributed greatly to our understanding of translation. The model of the A and P sites in the ribosome and the concept that the 50S ribosome contains the enzyme for peptidyl bond formation came from studies with the antibiotic. Puromycin is not a very useful antibiotic for treating bacterial diseases, however, because it also inhibits translation in eukaryotes, making it toxic in humans and animals. It is, however, one of the few antibiotics that is useful in archaeal genetics, with the availability of resistance cassettes.