Inactivation of GalU Leads to a Cell Wall-Associated Polysaccharide Defect That Reduces the Susceptibility of Enterococcus faecalis to Bacteriolytic Agents.

Enterococcal plasmid-encoded bacteriolysin Bac41 is a selective antimicrobial system that is considered to provide a competitive advantage to cells that carry the Bac41-coding plasmid. The Bac41 effector consists of the secreted proteins BacL and BacA, which attack the cell wall of the target cell to induce bacteriolysis. Here, we demonstrated that , which encodes UTP-glucose-1-phosphate uridylyltransferase, is involved in susceptibility to the Bac41 system in Spontaneous mutants that developed resistance to the antimicrobial effects of BacL and BacA were revealed to carry a truncation deletion of the C-terminal amino acid (aa) region 288 to 298 of the translated GalU protein. This truncation resulted in the depletion of UDP-glucose, leading to a failure to utilize galactose and produce the enterococcal polysaccharide antigen (EPA), which is expressed abundantly on the cell surface of This cell surface composition defect that resulted from or EPA-specific genes caused an abnormal cell morphology, with impaired polarity during cell division and alterations of the limited localization of BacL Interestingly, these mutants had reduced susceptibility to beta-lactams besides Bac41, despite their increased susceptibility to other bacteriostatic antimicrobial agents and chemical detergents. These data suggest that a complex mechanism of action underlies lytic killing, as exogenous bacteriolysis induced by lytic bacteriocins or beta-lactams requires an intact cell physiology in Cell wall-associated polysaccharides of bacteria are involved in various physiological characteristics. Recent studies demonstrated that the cell wall-associated polysaccharide of is required for susceptibility to bactericidal antibiotic agents. Here, we demonstrated that a mutation resulted in resistance to the enterococcal lytic bacteriocin Bac41. The homologue is reported to be essential for the biosynthesis of species-specific cell wall-associated polysaccharides in other In , the mutant lost the -specific cell wall-associated polysaccharide EPA (enterococcal polysaccharide antigen). The mutant also displayed reduced susceptibility to antibacterial agents and an abnormal cell morphology. We demonstrated here that was essential for EPA biosynthesis in , and EPA production might underlie susceptibility to lytic bacteriocin and antibiotic agents by undefined mechanisms.