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New expression system tightly controlled by zinc availability in Lactococcus lactis.
1Unité de Recherches Laitières et Génétique Appliquée, INRA, 78352 Jouy-en-Josas Cedex, France.
Applied and Environmental Microbiology
|September 4, 2004
Summary
A new P(Zn) zitR expression system for Lactococcus lactis was developed, controlled by zinc ion availability. This system shows strong induction during low zinc conditions and repression when zinc is abundant, offering tight regulation for gene expression.
Area of Science:
- Microbiology
- Molecular Biology
- Biotechnology
Background:
- Gene expression systems are crucial for recombinant protein production in bacteria.
- Lactococcus lactis is a widely used host for industrial applications.
- Existing expression systems may have limitations in inducibility or regulation.
Purpose of the Study:
- To develop and characterize a novel, zinc-inducible expression system in Lactococcus lactis.
- To evaluate the performance of the P(Zn) zitR system using reporter genes.
- To compare the P(Zn) zitR system with the established nisin-controlled expression (NICE) system.
Main Methods:
- Construction of a P(Zn) zitR-controlled expression vector in L. lactis.
- Utilized reporter genes: Staphylococcus aureus secreted nuclease (uspnuc) and Leuconostoc mesenteroides cytoplasmic beta-galactosidase (lacLM).
- Assessed enzyme activities and protein levels under varying zinc concentrations and compared with the NICE system.
Main Results:
- The P(Zn) zitR system demonstrated high inducibility upon divalent cation starvation (e.g., EDTA treatment or defined medium).
- Expression was strongly repressed in the presence of excess zinc.
- The P(Zn) zitR system showed comparable induction levels to the NICE system for lacLM, though NICE was fivefold more efficient; differences were minimal for nuclease detection.
Conclusions:
- The P(Zn) zitR system is a powerful and tightly regulated expression tool for L. lactis.
- Its expression is effectively controlled by the zinc concentration in the growth medium.
- This system offers a valuable alternative for controlled gene expression in L. lactis.
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