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MBio. 2018 Feb 13;9(1). pii: e02375-17. doi: 10.1128/mBio.02375-17.

Slowdown of Translational Elongation in Escherichia coli under Hyperosmotic Stress.

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Department of Physics, University of California at San Diego, La Jolla, California, USA.
School of Life Sciences, Central China Normal University, Wuhan, China.
Department of Microbiology and Ohio State Biochemistry Program, the Ohio State University, Columbus, Ohio, USA.
Department of Integrative Structural and Computational Biology, Department of Chemistry, the Skaggs Institute for Chemical Biology, the Scripps Research Institute, La Jolla, California, USA.
Department of Physics, University of California at San Diego, La Jolla, California, USA
Contributed equally


In nature, bacteria frequently experience many adverse conditions, including heat, oxidation, acidity, and hyperosmolarity, which all tend to slow down if not outright stop cell growth. Previous work on bacterial stress mainly focused on understanding gene regulatory responses. Much less is known about how stresses compromise protein synthesis, which is the major driver of cell growth. Here, we quantitatively characterize the translational capacity of Escherichia coli cells growing exponentially under hyperosmotic stress. We found that hyperosmotic stress affects bacterial protein synthesis through reduction of the translational elongation rate, which is largely compensated for by an increase in the cellular ribosome content compared with nutrient limitation at a similar growth rate. The slowdown of translational elongation is attributed to a reduction in the rate of binding of tRNA ternary complexes to the ribosomes.IMPORTANCE Hyperosmotic stress is a common stress condition confronted by E. coli during infection of the urinary tract. It can significantly compromise the bacterial growth rate. Protein translation capacity is a critical component of bacterial growth. In this study, we find for the first time that hyperosmotic stress causes substantial slowdown in bacterial ribosome translation elongation. The slowdown of translation elongation originates from a reduced binding rate of tRNA ternary complex to the ribosomes.


hyperosmotic stress; protein synthesis; ribosome content; translational elongation rate

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