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Unveiling the regulatory network controlling natural transformation in lactococci
Frédéric Toussaint1, Marie Henry de Frahan1, Félix Poncelet1
1Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
Plos Genetics
|July 1, 2024
Summary
We identified key growth conditions and regulators controlling natural DNA transformation in Lactococcus lactis. This research enables easier genetic manipulation of this important food fermentation bacterium.
Area of Science:
- Microbiology
- Molecular Biology
- Biotechnology
Background:
- Lactococcus lactis is crucial for food fermentation and biotechnology.
- Efficient genetic manipulation via natural transformation is needed to expand its applications.
- Understanding competence regulation in L. lactis is currently limited.
Purpose of the Study:
- To identify growth conditions that induce natural competence in L. lactis.
- To elucidate the regulatory network controlling the master regulator ComX.
- To explore the role of ComX degradation in competence.
Main Methods:
- Investigated effects of carbon source, nitrogen supply, and pH on competence.
- Analyzed the role of global regulators CcpA, CodY, and CovR in comX repression.
- Systematically inactivated known signaling systems.
- Studied the ComX-degrading MecA-ClpCP machinery.
Main Results:
- Carbon source, nitrogen, and pH were identified as key factors for competence.
- Global regulators CcpA, CodY, and CovR directly repress comX transcription.
- Classical pheromone-sensing regulators are not involved in competence.
- The MecA-ClpCP machinery plays a significant role in regulating competence, with a specific MecA mutation enhancing transformability.
Conclusions:
- L. lactis competence is regulated by environmental factors and global sensors (CcpA, CodY, CovR) and the MecA-ClpCP degradation system.
- This contrasts with regulatory mechanisms in related streptococci.
- Findings provide a foundation for using natural transformation to engineer L. lactis.
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