Cost-Benefit Tradeoffs in Engineered lac Operons

Abstract

Accounting for Lac When Escherichia coli expresses the lac operon, it needs to balance the potential increase in growth rate conferred through having the encoded proteins (which help it to take up and metabolize lactose) with the potential reduction in growth rate because of the resources needed to express and fold the encoded proteins. To investigate these inherent tradeoffs, Eames and Kortemme (p. 911 ) investigated the costs and benefits associated with the lac operon and surprisingly found that the main constraint on the system is not caused by the manufacture of the proteins themselves but by the lactose permease activity encoded by the LacY gene.