pLysE

pLysE is a bacterial expression plasmid used in Escherichia coli for recombinant protein production. It is part of the pET expression system family and is designed to improve control of target gene expression by co-expressing the enzyme T7 lysozyme, which inhibits T7 RNA polymerase. By reducing basal transcription from the T7 promoter, pLysE helps minimize leaky expression of proteins that can be toxic or burdensome to cells, enabling tighter induction of the target gene when needed.

The plasmid is typically used in conjunction with host strains that carry a DE3 lysogen, which provides T7 RNA polymerase. It is compatible with other pET-based expression plasmids within the same cell, allowing multi-plasmid setups for co-expression studies. Like other expression vectors, pLysE carries an antibiotic resistance marker for selection and an origin of replication suited to maintaining plasmid copy number in the host.

Development and use: pLysE was introduced as part of the family of plasmids designed to mitigate toxicity and leakiness associated with high-level T7-driven expression. It is commonly used when expressing proteins that show poor solubility or toxicity under standard expression conditions. Researchers often tailor induction parameters, temperature, and timing to maximize soluble yield while preserving cell viability.