Functional Characterization of the Chromosomal MazEF Toxin-Antitoxin Addiction System in Streptococcus mutans

• Main Author: Syed, Mohammad Adnan
• Other Authors: Lévesque, Céline
• Language: en_ca
• Published: 2011
• Subjects: toxin antitoxin system; streptococcus mutans; 0410; 0307; 0379
• Online Access: http://hdl.handle.net/1807/31458

Chromosomal toxin-antitoxin (TA) modules have been proposed to function as regulators of cell growth in response to environmental perturbations. The objective of this study was to characterize the MazEF TA system of the human pathogen Streptococcus mutans. Our data showed that the mazEF genes form a bicistronic operon. MazF toxin had a toxic effect on cells and this effect can be neutralized by coexpression of its cognate antitoxin MazE. Furthermore, we demonstrated that MazE and MazF proteins interact with each other in vivo, confirming the nature of this TA as a type II addiction system. We also demonstrated that MazF is a toxic nuclease arresting cell growth through the mechanism of RNA cleavage and that MazE inhibits the RNase activity of MazF by forming a protein complex. Our results suggest that the MazEF TA might represent a cell growth modulator facilitating the persistence of S. mutans in the oral cavity.