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Improved plasmid vectors with a thermoinducible expression and temperature-regulated runaway replication
Gene
|April 1, 1983
Summary
Researchers developed a new plasmid expression system using bacteriophage lambda
Area of Science:
- Molecular Biology
- Biotechnology
Background:
- Plasmid-based expression systems are crucial for recombinant protein production.
- Existing systems often face limitations in copy number control and promoter strength.
Purpose of the Study:
- To engineer a novel inducible expression vector for high-level protein production.
- To utilize bacteriophage lambda's strong promoter (pL) for enhanced gene expression.
Main Methods:
- Constructed a novel expression vector using runaway-replication mutants of plasmid R1.
- Integrated the bacteriophage lambda pL promoter, regulated by a temperature-sensitive repressor (cI gene).
- Introduced unique restriction enzyme sites (EcoRI, BamHI, XbaI, HindIII) downstream of the promoter.
Main Results:
- Achieved high-level expression of the T4 DNA-ligase gene.
- Demonstrated plasmid copy number amplification and promoter activation upon heat induction.
- T4 DNA ligase constituted approximately 20% of total cellular protein 3 hours post-induction.
Conclusions:
- The developed expression vector enables efficient, inducible, high-level protein production.
- This system is suitable for expressing genes requiring significant protein yields, such as T4 DNA ligase.