One was FT gene with T7 promoter (BBa_I719005) and 6His tag, and the other was FT gene only with T7 promoter. T7 promoter is a strong promotor regulated by T7 polymerase. In our strain of E.coli, the expression of T7 polymerase can be induced by IPTG. 6His tag, which is used in later steps, enabled us to purify FT protein from E.coli using affinity chromatography.