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Parameters affecting gene expression from the Pm promoter in gram-negative bacteria
H C Winther-Larsen1, K D Josefsen, T Brautaset
1UNIGEN Center for Molecular Biology and Department of Biotechnology, Norwegian University of Science and Technology, Trondheim.
Metabolic Engineering
|August 10, 2000
Summary
The Pm promoter system allows tunable gene expression in gram-negative bacteria like Escherichia coli and Pseudomonas aeruginosa. Optimizing growth medium pH is crucial for controlling expression levels, enabling applications like xanthan biosynthesis regulation.
Area of Science:
- Molecular Biology
- Microbial Genetics
Background:
- The Pm promoter is a versatile system for regulating gene expression in gram-negative bacteria.
- The XylS regulator activates the Pm promoter in response to specific benzoic acid derivatives.
Purpose of the Study:
- To investigate the factors influencing Pm promoter expression in different bacterial hosts.
- To optimize Pm promoter activity for controlled gene expression and biotechnological applications.
Main Methods:
- Chromosomal and plasmid-based insertion of the Pm promoter in Escherichia coli and Pseudomonas aeruginosa.
- Analysis of gene expression levels under varying environmental conditions (carbon source, dissolved oxygen, pH).
- Demonstration of Pm promoter utility in controlling xanthan biosynthesis in Xanthomonas campestris.
Main Results:
- Substituted benzoic acid derivatives induced Pm expression with similar relative rankings in both E. coli and P. aeruginosa, but with different kinetics.
- Growth medium pH was identified as a critical factor significantly impacting Pm expression levels.
- Expression levels could be modulated over a 10,000- to 100,000-fold range by combining genetic and environmental parameters.
Conclusions:
- The Pm promoter system offers a tunable platform for gene expression in diverse gram-negative bacteria.
- Optimizing pH is essential for maximizing the control and range of Pm promoter activity.
- The Pm promoter is a valuable tool for applications such as metabolic engineering, exemplified by controlling xanthan production.