Expression of mptC of Listeria monocytogenes induces sensitivity to class IIa bacteriocins in Lactococcus lactis

Area of Science:

• Microbiology
• Molecular Biology
• Bacteriology

Background:

• Bacteriocin resistance mechanisms are crucial for understanding microbial interactions.
• Listeria monocytogenes exhibits sensitivity to class IIa bacteriocins, linked to its mannose phosphotransferase system (PTS) permease.
• Lactococcus lactis is generally insensitive to class IIa bacteriocins.

Purpose of the Study:

• To investigate the role of the mannose phosphotransferase system (PTS) permease in class IIa bacteriocin activity.
• To determine if heterologous expression of the mptACD operon confers bacteriocin sensitivity to an insensitive species.
• To elucidate the specific genes within the mptACD operon responsible for bacteriocin sensitivity.

Main Methods:

• Heterologous expression of the mptACD operon from Listeria monocytogenes in Lactococcus lactis using the NICE double plasmid system.
• Assessment of class IIa bacteriocin (leucocin A, pediocin PA-1, enterocin A) inhibitory activity against recombinant Lactococcus lactis.
• Site-directed mutagenesis and PCR to generate derivative plasmids and investigate the function of individual mptACD genes.

Main Results:

• Recombinant Lactococcus lactis expressing the mptACD operon became sensitive to leucocin A, pediocin PA-1, and enterocin A.
• Expression of the mptC gene alone was sufficient to confer sensitivity to class IIa bacteriocins in Lactococcus lactis.
• The mptACD operon is directly involved in mediating sensitivity to class IIa bacteriocins.

Conclusions:

• The mannose phosphotransferase system (PTS) permease, encoded by the mptACD operon, is a key determinant of class IIa bacteriocin sensitivity.
• The mptC gene product is the primary component responsible for conferring bacteriocin sensitivity.
• This study provides insights into the molecular mechanisms of bacteriocin-host interactions and potential strategies for controlling bacterial growth.