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Cell Rep. 2014 Jun 12;7(5):1521-1533. doi: 10.1016/j.celrep.2014.04.033. Epub 2014 May 15.

The dynamics of SecM-induced translational stalling.

Author information

1
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305-5126, USA; Department of Applied Physics, Stanford University, Stanford, CA 94305-4090, USA.
2
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305-5126, USA.
3
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305-5126, USA; Stanford Magnetic Resonance Laboratory, Stanford University School of Medicine, Stanford, CA 94305-5126, USA. Electronic address: puglisi@stanford.edu.

Abstract

SecM is an E. coli secretion monitor capable of stalling translation on the prokaryotic ribosome without cofactors. Biochemical and structural studies have demonstrated that the SecM nascent chain interacts with the 50S subunit exit tunnel to inhibit peptide bond formation. However, the timescales and pathways of stalling on an mRNA remain undefined. To provide a dynamic mechanism for stalling, we directly tracked the dynamics of elongation on ribosomes translating the SecM stall sequence (FSTPVWISQAQGIRAGP) using single-molecule fluorescence techniques. Within 1 min, three peptide-ribosome interactions work cooperatively over the last five codons of the SecM sequence, leading to severely impaired elongation rates beginning from the terminal proline and lasting four codons. Our results suggest that stalling is tightly linked to the dynamics of elongation and underscore the roles that the exit tunnel and nascent chain play in controlling fundamental steps in translation.

PMID:
24836001
PMCID:
PMC4059775
DOI:
10.1016/j.celrep.2014.04.033
[Indexed for MEDLINE]
Free PMC Article

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