Cost of Unneeded Proteins in E. coli Is Reduced after Several Generations in Exponential Growth

Irit Shachrai, Alon Zaslaver, Uri Alon*, Erez Dekel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

151 Scopus citations


When E. coli cells express unneeded protein, they grow more slowly. Such penalty to fitness associated with making proteins is called protein cost. Protein cost is an important component in the cost-benefit tradeoffs that underlie the evolution of protein circuits, but its origins are still poorly understood. Here, we ask how the protein cost varies during the exponential growth phase of E. coli. We find that cells growing exponentially following an upshift from overnight culture show a large cost when producing unneeded proteins. However, after several generations, while still in exponential growth, the cells enter a phase where cost is much reduced despite vigorous unneeded protein production. We find that this reduced-cost phase depends on the ppGpp system, which adjusts the amount of ribosomes in the cell and does not occur after a downshift from rich to poor medium. These findings suggest that protein cost is a transient phenomenon that happens upon an upshift in conditions and that cost is reduced when ribosomes and other cellular systems have increased to their appropriate steady-state level in the new condition.

Original languageAmerican English
Pages (from-to)758-767
Number of pages10
JournalMolecular Cell
Issue number5
StatePublished - 11 Jun 2010
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by the Kahn Family Foundation.




Dive into the research topics of 'Cost of Unneeded Proteins in E. coli Is Reduced after Several Generations in Exponential Growth'. Together they form a unique fingerprint.

Cite this