Fig 5.

Secretion efficiencies of clones selected from Usp45TM8 silent mutation library compared to clones from Usp45sp silent mutation library. α-Amylase activity (normalized to the amount secreted by wild-type Usp45sp at 10 ng/ml nisin) was plotted against ΔG of the RBS for induction at (A) 0.1 ng/ml, (B) 1 ng/ml, and (C) 10 ng/ml nisin for Usp45TM8 silent mutation clones (black squares; Usp45sp silent mutation clones as described for Fig. 3 are shown as gray diamonds for comparison). The data represent the means ± SEM of the results of three independent experiments. Simulation results show protein expression levels against folding energy for (D) low (3.2 μM), (E) medium (32 μM), and (F) high (32 μM) mRNA transcript levels. Solid black lines represent Usp45TM8 silent mutation clones, and dashed gray lines represent Usp45sp silent mutation clones (data from Fig. 3).