Fig 6.

Effect of the ΔrneG mutation on the expression of the aceA-lacZ fusion genes. (A) β-Galactosidase activity in ATCC 31831 (wild type) and D2281 (ΔrneG) cells harboring the pA5UZ plasmid. Plasmid pA5UZ carries the aceA 5′-UTR-lacZ fusion gene. A schematic diagram of the aceA 5′-UTR-lacZ fusion gene and the aceA promoter paceA is shown at the top. The wild type and the ΔrneG mutant were grown on CGC minimal medium containing either 1% sodium acetate (filled bars) or 1% glucose (blank bars). (B) β-Galactosidase activity in ATCC 31831 and D2281 cells harboring the pZA3U plasmid. Plasmid pZA3U carries the lacZ-aceA 3′-UTR fusion gene. A schematic diagram of the lacZ-aceA 3′-UTR fusion gene and the trc promoter ptrc is shown at the top. The wild type and the ΔrneG mutant were grown on CGC minimal medium containing either 1% sodium acetate (filled bars) or 1% glucose (blank bars). To synthesize the LacZ protein from the lacZ-aceA 3′-UTR fusion gene, IPTG was added to a final concentration of 0.1 mM. Enzyme activity is expressed in Miller units. All the values are derived from at least three independent cultivations, and the error bars represent the standard deviations. (C) Expression of the LacZ protein expressed from the pA5UZ and pZA3U plasmids was examined by 7.5% SDS-PAGE. The position of the LacZ protein is shown to the right of the gel.