Getting Past Polyproline Pauses

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Science  04 Jan 2013:
Vol. 339, Issue 6115, pp. 38-39
DOI: 10.1126/science.1233338

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The ribosome is a versatile enzyme, but it cannot synthesize all proteins equally well—certain combinations of amino acids pose problems. Ribosome stalling by fairly long amino acid motifs can regulate gene expression in a variety of organisms, from bacteria to humans (1, 2). In these cases, the nascent peptide interacts with the peptide exit channel of the ribosome to induce a conformation that prevents peptide bond formation. Two papers in this issue, by Doerfel et al. on page 85 (3) and Ude et al. on page 82 (4), reveal that stalling is common and fundamental: Short, proline (Pro)–rich motifs impede protein synthesis, and stalling is alleviated by a poorly understood elongation factor, EF-P. These studies offer a model of the biological function and mechanism of EF-P through a convergence of biochemical and genetic methods.