Figure 2.—

Competition experiments to test for the cost of amino acid usage and cost of production on glucose. A constitutive ssrA-tagged strain (DMS1397) competed against a constitutive strain (DMS269, open circles) and against a regulated strain (DMS267, solid circles). (B) The constitutive ΔRBS strain (DMS1360) competed against the constitutive strain (DMS269, open circles) and regulated strain (DMS267, solid circles). In A and B, the line is the selection difference between regulated and constitutive, 10.28%/generation. (A) The ssrA tag, which recycles protein, does not alleviate the cost of expression. (B) Abolishing the act of production alleviates all of the cost of expression.