Fig. 4. Functional complementation of Cys^- E. coli NK3 by transformation with the expression vector carrying soybean OAS-TL cDNA clone. The E. coli cysteine-auxotroph was transformed with pSCS10 and was streaked on M9 minimal agar plates with 0.5 mM cysteine (right plate) or without cysteine (left plate). The empty vector pET28a was used as a negative control.