Joanna Joo
New York University
Targeting Surface Polysaccharide Production in Gram-negative Bacteria
Gram-negative bacteria contain an outer membrane (OM) composed of diverse surface sugar polymers that influence variability in host-pathogen interactions and limit the permeability of some antibiotics. O-antigens (O-Ags) present on the distal region in lipopolysaccharide (LPS) of the OM and serve as a virulence factor. The ability to perturb the biosynthesis of O-Ag would potentially decrease intrinsic resistance in Gram-negative bacteria and increase the entry of some antibiotics. In this work, we aim to disrupt the O-Ag biosynthesis pathway. Previous O-Ag inhibitors have shown limitation against E. coli and other Gram-negative bacteria with low permeability. Here, we aimed to develop a cell-based screening assay for discovery of E. coli permeable O-Ag inhibitors, utilizing O-Ag knockout strains. Small scale screening was conducted with antibiotics, and one well-known antibiotic was found to be potential O-Ag biosynthesis inhibitor. The addition of compound caused slight decrease in the long O-Ag formation with significant accumulation of short O-Ag, suggesting inhibition of O-Ag polymerization. Following-up testing suggested that the compound might directly inhibit O-Ag polymerase complex in a strain-specific manner. Ongoing work will reveal compound’s mechanism of action on O-Ag biosynthesis. This work will aid in the discovery of scaffolds to develop new strategies to stall the synthesis of bacterial virulence factors and reveal alternative targets of known antibiotics.
Gram-negative bacteria contain an outer membrane (OM) composed of diverse surface sugar polymers that influence variability in host-pathogen interactions and limit the permeability of some antibiotics. O-antigens (O-Ags) present on the distal region in lipopolysaccharide (LPS) of the OM and serve as a virulence factor. The ability to perturb the biosynthesis of O-Ag would potentially decrease intrinsic resistance in Gram-negative bacteria and increase the entry of some antibiotics. In this work, we aim to disrupt the O-Ag biosynthesis pathway. Previous O-Ag inhibitors have shown limitation against E. coli and other Gram-negative bacteria with low permeability. Here, we aimed to develop a cell-based screening assay for discovery of E. coli permeable O-Ag inhibitors, utilizing O-Ag knockout strains. Small scale screening was conducted with antibiotics, and one well-known antibiotic was found to be potential O-Ag biosynthesis inhibitor. The addition of compound caused slight decrease in the long O-Ag formation with significant accumulation of short O-Ag, suggesting inhibition of O-Ag polymerization. Following-up testing suggested that the compound might directly inhibit O-Ag polymerase complex in a strain-specific manner. Ongoing work will reveal compound’s mechanism of action on O-Ag biosynthesis. This work will aid in the discovery of scaffolds to develop new strategies to stall the synthesis of bacterial virulence factors and reveal alternative targets of known antibiotics.
