Figure 1.—
Effect of β-lactamase genes on E. coli growth rates. (A) Growth curves in LB broth of E. coli K12 XL1-Blue containing pTP123, pTP123-TEM-1, or pTP123-SME-1 were obtained by monitoring OD600 over time. (B) Growth curves of a frameshifted SME-1 clone and point mutants that eliminate enzymatic activity (S70A:E166Q) or disulfide bond formation (C69V:C238V). (C) Growth curves of chimeric constructs in which signal sequences of TEM-1 and SME-1 have been exchanged. Error bars represent standard deviation of at least three independent experiments.