Figure 2

Solubility of DXP enzymes in E. coli. The expression systems and incubation temperatures played important roles in production of soluble proteins. All the enzymes in the DXP pathway were individually expressed by three expression systems (A: BL21 strain - T7 promoter; B: M15 strain - T5 promoter; C: DH10B strain - araBAD promoter) at two temperatures (37°C and 20°C). Presented data were average of triplicates and standard errors were drawn on the plot. The quantifications were based on image of SDS-PAGE gels, some of which (the set for DH10B strain – araBAD promoter, 20°C) were demonstrated in D. S: soluble protein fraction; IS: insoluble protein fraction. The pictures of DXP proteins were cropped from individual gel images and aligned for demonstration purpose. The protein solubilities were generally higher in 20°C than those in 37°C in all systems (Figure 2A-C).