Cost-benefit tradeoffs in engineered lac operons.
Cells must balance the cost and benefit of protein expression to optimize organismal fitness. The lac operon of the bacterium Escherichia coli has been a model for quantifying the physiological impact of costly protein production and for elucidating the resulting regulatory mechanisms. We report quantitative fitness measurements in 27 redesigned operons that suggested that protein production is not the primary origin of fitness costs. Instead, we discovered that the lac permease activity, which relates linearly to cost, is the major physiological burden to the cell. These findings explain control points in the lac operon that minimize the cost of lac permease activity, not protein expression. Characterizing similar relationships in other systems will be important to map the impact of cost/benefit tradeoffs on cell physiology and regulation.
Graduate Group in Biophysics, MC 2530, University of California, San Francisco, CA 94158-2330, USA.
SourceScience (New York, N.Y.) 336:6083 2012 May 18 pg 911-5
Escherichia coli Proteins
Gene Expression Regulation, Bacterial
Gene Knockout Techniques
Molecular Sequence Data
Monosaccharide Transport Proteins
Pub Type(s)Journal Article
Research Support, Non-U.S. Gov't