Cellodextrin Metabolism and Phosphotransferase System-Catalyzed Uptake in Enterococcus faecalis.

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Enterococcus faecalis possesses complex carbohydrate uptake systems.
• Phosphotransferase systems (PTS) are crucial for nutrient transport and metabolism in bacteria.
• Understanding β-glucoside transport is key to bacterial physiology and potential biotechnological applications.

Purpose of the Study:

• To identify and characterize the PTS transporters responsible for cellobiose and short cellooligosaccharide uptake in Enterococcus faecalis.
• To elucidate the roles of specific EII proteins (EIIA, EIIB, EIIC) in the transport mechanism.
• To investigate the regulation of the identified gene locus.

Main Methods:

• Genetic and molecular biology techniques were employed to identify and analyze the genes encoding the PTS transporters.
• Functional characterization of the EII proteins (CelA1, CelB1, CelB2, CelC1, CelC2) involved in β-glucoside transport.
• Analysis of the operonic structures and regulatory elements, including the identification of the transcription activator CelR.

Main Results:

• Two distinct PTS transporters, CelC1 and CelC2, were identified for cellobiose and short cellooligosaccharides.
• The EIIA component (CelA1) is essential for multiple β-glucoside uptakes, including diheterosides.
• Cellooligosaccharides are preferably transported by CelC1 (di-saccharides) or CelC2 (≥4 residues), with tri-saccharides utilizing both.
• CelA1B1C1 is the primary transporter for cellobiose and chitobiose, also involved in laminaribiose and sophorose uptake.
• The CelA1B2C2 transporter requires unknown accessory proteins CelGHI.
• A network of β-glucoside uptake pathways exists, regulated by CelR.

Conclusions:

• Enterococcus faecalis employs a sophisticated PTS network for efficient uptake of diverse β-glucosides.
• The identified transporters exhibit substrate specificity based on oligosaccharide size and structure.
• The regulatory mechanism involving CelR suggests coordinated control over β-glucoside metabolism.