Antibiotic Bouncer

Contrary to previous assumptions that macrolide antibiotics completely block the exit tunnel of ribosomes, new evidence shows that some peptides are allowed to pass.

kerry grens
Kerry Grens

Kerry served as The Scientist’s news director until 2021. Before joining The Scientist in 2013, she was a stringer for Reuters Health, the senior health and science reporter at...

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LEAKY PLUG: Binding of the antibiotic erythromycin (orange) during protein translation stops the ribosome (gray) from producing most proteins, except those with a particular N-terminal sequence.COURTESY OF ALEXANDER MANKIN

The paper
K. Kannan et al., “Selective protein synthesis by ribosomes with a drug-obstructed exit tunnel,” Cell, 151:508-20, 2012.

The finding
Macrolides are widely used antibiotics that are thought to act by binding to and plugging up the ribosome, thereby halting protein translation. But “several reports in the past didn’t fit too snugly in this model,” says Alexander Mankin of the University of Illinois at Chicago. He and his colleagues retested the assumption by treating E. coli with high doses of the macrolide erythromycin and found that some proteins were still translated.

The selectivity
Mankin’s group found that translation was not halted completely, but rather declined by about 94 percent, and that the successfully...

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