Antibiotic Inhibition of Translation

Figure 27.28 shows a few of the important antibiotics that act by inhibiting translation. Many translation-inhibiting antibiotics work selectively on prokaryotic organisms because the process of translation is sufficiently different in them than it is in humans. Thus, these compounds can be used to treat bacterial infections with minimal side effects to humans.

Microorganisms develop resistance to many antibiotics often through acquisition of a particular "resistance gene." When bacteria carrying a resistance gene are treated with the drug, only resistant bacteria will grow.

Actions of the common antibiotics are as follows:

> Tetracycline - Inhibits binding of aminoacyl tRNAs to the ribosome and thereby blocks continued translation.

> Streptomycin - Interferes with normal pairing between aminoacyl tRNAs and message codons, causing misreading, and thereby producing aberrant proteins.

> Erythromycin - Binds to a specific site on the 23S RNA and blocks elongation by interfering with the translocation step.

> Chloramphenicol - Blocks elongation, apparently by acting as competitive inhibitor for the peptidyltransferase complex. The amide link in the molecule resembles a peptide bond.

> Puromycin - Causes premature chain termination. Part of the molecule resembles the 3' end of the aminoacylated tRNA. It will enter the A site and transfer to the growing chain, causing premature chain release.

See also: Initiation of Translation, Elongation of Translation, Termination of Translation