Broad host range, regulated expression system utilizing bacteriophage T7 RNA polymerase and promoter (original) (raw)

1993, Biotechnology and Bioengineering

An IPTG-regulated broad host range expression system was constructed using compatible broad host range plasmids, the T7 RNA polymerase, and T7 promoter sequences. The system is implemented by the coexistence of two plasmids. The first contains the T7 RNA polymerase gene under the control of lac/ or lacP genes and lacUV5 promoter. The second encodes the T7 promoter upstream of a multicloning site. IncPl or IncP4 77 promoter plasmids, and IncP1, IncP4 or lncW T7 RNA polymerase plasmids were constructed. The expression from the IncPl promoter plasmids in the presence of the IncP4 polymerase plasmids was tested by in vivo IacZ fusions and in vivo labeling of proteins. In this combination, the use of lacP improves the regulation levels in Escherichia coli, whereas, in Pseudomonas phaseolicola, a 28.5-fold regulation was obtained with lacl. Although the level of IacZexpression from the T7 promoter in P. phaseolicola is low compared with €. coli, it is similar to levels obtained with the pm promoter in Pseudomonas putida when the differences in the copy number of the expression vectors are taken into consideration.

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