A chromosomal expression vector for Escherichia coli based on the bacteriophage Mu

Area of Science:

• Molecular Biology
• Biotechnology
• Microbial Genetics

Background:

• Traditional expression vectors in Escherichia coli are often plasmids, which can be unstable without selective pressure.
• Instability of expression vectors can lead to loss of genetic material and reduced protein yields.
• Bacteriophage Mu offers unique genetic elements that can be leveraged for novel vector design.

Purpose of the Study:

• To develop a novel, highly stable expression vector for Escherichia coli.
• To utilize bacteriophage Mu elements for chromosomal integration and inducible gene expression.
• To achieve high-level production of heterologous proteins in a stable expression system.

Main Methods:

• Construction of a chromosome-based expression vector derived from bacteriophage Mu.
• Integration of heterologous genes under the control of the Mu middle promoter.
• Induction of vector replication and protein synthesis via temperature shift.
• Analysis of protein expression levels in different Escherichia coli strains.

Main Results:

• The developed vector demonstrated extreme stability, even without selective pressure, due to its chromosomal integration.
• Replication and heterologous protein synthesis were successfully induced by a temperature shift.
• Four different proteins (beta-galactosidase, chloramphenicol acetyltransferase, porcine somatotropin, human growth hormone) were produced at levels of 5–20% of total cell protein.
• Expression levels were influenced by the growth medium, with highest yields observed in rich media.

Conclusions:

• A stable, chromosome-based expression vector system for Escherichia coli has been successfully developed using bacteriophage Mu.
• The vector allows for inducible and high-level production of heterologous proteins.
• This system offers a promising alternative to traditional plasmid-based vectors for recombinant protein expression in E. coli.