An improved beta-galactosidase reporter gene

Area of Science:

• Molecular Biology
• Gene Expression
• Biotechnology

Background:

• The native E. coli beta-galactosidase gene is often used as a reporter gene in mammalian cells.
• Challenges exist in achieving high expression levels and efficient detection with the native gene sequence.

Purpose of the Study:

• To codon-optimise the E. coli beta-galactosidase gene for enhanced expression in mammalian cells.
• To evaluate the performance of the codon-optimised gene as a marker/reporter in lentiviral vectors.

Main Methods:

• Codon optimisation of the E. coli beta-galactosidase gene sequence.
• Expression analysis in mammalian cells.
• RNA stability and translational efficiency assessment.
• Lentiviral construct generation and titration using 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside staining.
• Southern blot analysis for transduced cell detection.
• Analysis of splice acceptor sites and RNA splicing.

Main Results:

• Codon optimisation resulted in a 15-fold increase in beta-galactosidase expression in mammalian cells.
• Enhanced transcript stability and translational efficiency contributed to increased expression.
• Lentiviral constructs with the codon-optimised gene showed a five-fold increase in apparent titre.
• Southern blot analysis indicated increased efficiency in detecting transduced cells.
• Codon optimisation eliminated cryptic splice acceptor sites, improving RNA processing.

Conclusions:

• The codon-optimised beta-galactosidase gene offers significant advantages as a marker/reporter gene in mammalian cells compared to the native sequence.
• Improved expression, enhanced detection, and better RNA processing make it suitable for lentiviral applications.
• A variant with a nuclear localisation signal was also developed for specific applications.