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Enterococcus faecalis MalR acts as a repressor of the maltose operons and additionally mediates their catabolite
Maxime Grand1, Victor Sebastián Blancato2, Martín Espariz2
1Normandie Université, UNICAEN, Caen, France.
Abstract:
Enterococci are gram-positive pathogens and lead to cause hospital-acquired infections worldwide. Central carbon metabolism was shown as highly induced in Enterococcus faecalis during infection context. Metabolism of α-polysaccharides was previously described as an important factor for host colonisation and biofilm formation. A better characterisation of the adaptation of this bacterium to carbohydrate availabilities may lead to a better understanding of the link between carbohydrate metabolism and the infection process of E. faecalis. Here we show that MalR, a LacI/GalR transcriptional regulator, is the main factor in the regulation of the two divergent operons involved in maltose metabolism in this bacterium. The malR gene is transcribed from the malP promoter, but also from an internal promoter inside the gene located upstream of malR. In the absence of maltose, MalR acts as a repressor and in the presence of glucose, it exerts efficient CcpA-independent carbon catabolite repression. The central PTS protein P-Ser-HPr interacts directly with MalR and enhances its DNA binding capacity, which allows E. faecalis to adapt its metabolism to environmental conditions.
Insights
Enterococcus faecalis uses MalR to control maltose metabolism, adapting to nutrient availability during infections. This regulation is crucial for understanding how carbohydrate metabolism influences E. faecalis pathogenicity.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- Enterococci are significant causes of hospital-acquired infections.
- Central carbon metabolism is upregulated in Enterococcus faecalis during infection.
- α-polysaccharide metabolism is vital for Enterococcus faecalis host colonization and biofilm formation.
Purpose of the Study:
- To characterize the adaptation of Enterococcus faecalis to varying carbohydrate availability.
- To understand the link between carbohydrate metabolism and E. faecalis infection processes.
- To identify the key regulator of maltose metabolism in E. faecalis.
Main Methods:
- Investigated the role of MalR, a LacI/GalR transcriptional regulator.
- Analyzed the regulation of two divergent operons involved in maltose metabolism.
- Studied the interaction between MalR and the central PTS protein P-Ser-HPr.
Main Results:
- MalR is identified as the primary regulator of maltose metabolism operons in E. faecalis.
- MalR functions as a repressor in the absence of maltose and mediates CcpA-independent carbon catabolite repression in the presence of glucose.
- P-Ser-HPr enhances MalR's DNA binding capacity, facilitating metabolic adaptation.
Conclusions:
- MalR plays a critical role in regulating maltose metabolism and bacterial adaptation to environmental conditions.
- Understanding MalR's function provides insights into Enterococcus faecalis pathogenesis.
- The interaction with P-Ser-HPr highlights a novel mechanism for metabolic control in bacteria.
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