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High-level expression of the human tumor necrosis factor-alpha
Chinese Journal of Biotechnology
|January 1, 1995
Summary
Optimizing synthetic tumor necrosis factor-alpha (TNF-alpha) gene expression in E. coli requires careful consideration of the translation initiation region. A 6bp distance and minimal secondary structure energy yielded the highest protein expression levels.
Area of Science:
- Molecular Biology
- Protein Expression
- Synthetic Biology
Background:
- Tumor necrosis factor-alpha (TNF-alpha) is a crucial cytokine with therapeutic potential.
- Efficient production of recombinant TNF-alpha is essential for research and clinical applications.
- Optimizing gene expression in bacterial systems like E. coli can be challenging due to regulatory elements.
Purpose of the Study:
- To investigate the impact of translation initiation region parameters on the expression of a chemically synthesized tumor necrosis factor-alpha (TNF-alpha) gene in E. coli.
- To identify optimal plasmid designs for maximizing TNF-alpha protein yield.
- To evaluate the role of codon optimization in enhancing gene expression.
Main Methods:
- Construction of five expression plasmids differing in the distance (D) between the Shine-Dalgarno (SD) sequence and the initiation codon (ATG).
- Analysis of the thermodynamic stability (delta G0f298) of secondary structures in the translation initiation region.
- Quantification of TNF-alpha expression levels as a percentage of total bacterial proteins.
- Comparison of expression between a fully codon-optimized synthetic gene and a partially modified gene.
Main Results:
- The plasmid with a 6bp distance (D) and the lowest absolute delta G0f298 value exhibited the highest TNF-alpha expression, reaching up to 60% of total bacterial proteins.
- Codon usage significantly influences protein expression levels in E. coli.
- A fully codon-optimized synthetic TNF-alpha gene demonstrated substantially higher expression compared to a partially modified gene.
Conclusions:
- The distance between the SD sequence and the ATG initiation codon, along with the secondary structure stability in the translation initiation region, are critical factors for high-level protein expression.
- Codon optimization for the host organism (E. coli) is a key strategy for maximizing the yield of synthetic genes.
- These findings provide valuable insights for designing expression vectors for recombinant protein production.