Figure 4

Synthetic cysE and cysM gene transformants display recovery of CysE function without cysteine and methionine and CysM function without cysteine. (A) E. coli ΔcysE competent cells were transformed with positive control cysE, two cysE variants cysE-C/cysE-CM cloned into the multiple cloning site of pUC19 plasmid, and original pUC19 encoding N-terminal fragment of lacZα as a negative control. (B) E. coli ΔcysMΔcysK competent cells transformed with positive control cysM, two cysM variants cysM-C/cysM-CM in pUC19 plasmid, and original pUC19 encoding N-terminal fragment of lacZα as a negative control. Cells were plated on M9 + glucose medium with 0.4 mM IPTG, 50 μg/ml kanamycin, and 100 μg/ml ampicillin and incubated at 30 °C for 72 h.