Ribosome recycling is not critical for translational coupling in E. coli

We used ribosome profiling to characterize the biological role of ribosome recycling factor (RRF) in E. coli. As expected, RRF depletion leads to enrichment of post-termination 70S complexes in 3′-UTRs. We also observe that elongating ribosomes are unable to complete translation because they are blocked by non-recycled ribosomes at stop codons. Previous studies have suggested a role for recycling in translational coupling within operons; if a ribosome remains bound to an mRNA after termination, it may re-initiate downstream. We found, however, that RRF depletion did not significantly affect coupling efficiency in reporter assays or in ribosome density genome-wide. These findings argue that re-initiation is not a major mechanism of translational coupling in E. coli. Finally, RRF depletion has dramatic effects on the activity of ribosome rescue factors tmRNA and ArfA. Our results provide a global view of the effects of the loss of ribosome recycling on protein synthesis in E. coli.

Article and author information

Author details

Kazuki Saito

Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, United States
Competing interests
No competing interests declared.


National Institute of General Medical Sciences (GM110113)

Howard Hughes Medical Institute

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

Joseph T Wade, Wadsworth Center, New York State Department of Health, United States

Publication history

Received: June 13, 2020
Accepted: September 22, 2020
Accepted Manuscript published: September 23, 2020 (version 1)


© 2020, Saito et al.This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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