pNEW Inducible Gene Expression System in E coli
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current gene expression systems in Escherichia coli, such as those using IPTG or temperature shifts, are costly, toxic, and lack precise regulation, limiting their suitability for industrial-scale production of recombinant proteins and bulk chemicals.
Innovation Solution
A novel inducible expression system, pNEW, utilizing regulatory elements from Pseudomonas putida, which includes a synthetic operator and repressor complex activated by cumate and its derivatives, providing tight regulation and high induction levels of gene expression in E. coli.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If IPTG is used as inducer in lacUV5/tac/PT7 expression systems, then gene expression can be easily regulated, but the system becomes costly and toxic for industrial-scale production
Solution Approach 1:
The patent replaces expensive and toxic IPTG with a cheap, non-toxic inducer system based on cumulative metabolites from central carbon metabolism. The inducer is generated endogenously through metabolic pathways, eliminating the need for external addition of costly chemicals, thus resolving the cost and toxicity issues while maintaining ease of regulation.
Solution Approach 2:
The patent introduces a repressor protein that binds to an operator sequence to control gene expression. This intermediary mechanism allows for tight regulation without requiring toxic inducers like IPTG. The repressor-operator system provides a natural, non-toxic means of controlling transcription, replacing the need for external chemical inducers.
2Productivity
If temperature shift is used to induce lambda PL and lambda PR promoters, then gene expression can be activated, but protein folding is adversely affected and final yield is reduced
Solution Approach 1:
The patent changes the induction parameter from temperature shift to chemical inducer (cumulative metabolites). This allows gene expression to be activated at constant temperature, preventing thermal stress on the protein folding process while maintaining high expression levels. The chemical induction mechanism provides a gentler, more reliable alternative to thermal shock.
3Productivity
If strong promoter sequences are used to enhance gene expression, then transcriptional expression is enhanced, but basal expression cannot be completely repressed
Solution Approach 1:
The patent employs a repressor protein that provides negative feedback control by binding to the operator sequence and blocking RNA polymerase. This feedback mechanism ensures that even strong promoters cannot drive basal expression when the repressor is bound, achieving precise control over expression levels. The repressor-operator interaction creates a switch that can completely turn off expression in the absence of inducer.
Data Source
AI summary
An expression system for transforming E coll with a nucleic acid molecule of interest has an operator sequence of a cmt operon operatively linked to a promoter for the operator, and, a repressor sequence from a cym operon operatively linked to a promoter for the repressor. The expression system may have a nucleic acid molecule of interest, for example, a nucleic acid molecule that encodes a protein. Any type of E coll host cells may be transformed with the expression system. A method of producing a protein involves transforming an E coll host cell with the expression system having a nucleic acid molecule that codes for a protein, and, culturing the host cell in a culture medium under conditions in which the nucleic acid molecule will express the protein.