Characterization of Zymomonas mobilis promoters that are functional in Escherichia coli.

Zymomonas mobilis ZM4 is a gram-negative, facultative anaerobic, natural ethanologenic bacterium used in industrial production of bio-products. For expression of genes, promoters are required. However, most of the promoters reported from Z. mobilis poorly function in Escherichia coli. This makes the process of expression and screening labor-intensive. In the present study, we compared the strengths of two Z. mobilis promoters, P chap and P pap , which drive the expression of chaperonin and phosphatase PAP2 family protein, respectively, with P tac promoter. In E. coli , the P tac promoter was found to be the strongest followed by P pap and P pdc , while in Z. mobilis , P pdc was found to be the strongest and P chap the weakest promoter. Further characterization of the promoters was done by cloning the gfp uv gene which expresses the green fluorescent protein, under their control and measuring the fluorescence of the E. coli transformants. The activity of these promoters was also studied at different pH (pH 5, 7 and 9) and different temperatures (30°C, 37°C and 42°C) in exponential and stationary phases. Both P chap and P pap promoters showed higher activity in stationary phase than in exponential phase. Since the promoters were active at all temperatures and pH studied, they can be used for gene expression in E. coli under desired environmental conditions. • Spacer lengths and −10 and −35 box sequences of P chap and P pap promoters determined. • The promoters' strengths determined by cloning gfp uv gene under their control. • The strong promoter of Zymomonas mobilis , P pdc , found to be a weak promoter in Escherichia coli. • In E. coli , P tac promoter was the strongest followed by P pap and P pdc. [ABSTRACT FROM AUTHOR]