Conserved mechanism of cell-wall synthase regulation revealed by the identification of a new PBP activator in Pseudomonas aeruginosa

Significance Penicillin-binding proteins (PBPs) are synthases that build the bacterial cell wall. They are one of our most important antibiotic targets. Several years ago, it was shown that a major PBP synthase of the Gram-negative bacterium Escherichia coli requires activation by LpoB. This outer-membrane lipoprotein is narrowly conserved in Gram-negative species whereas its target PBP synthase is broadly distributed. Here, we show that Pseudomonas aeruginosa and other Gram-negative bacteria use the distinct lipoprotein called LpoP to activate their PBPs via a mechanism similar to LpoB-PBP activation in E. coli . Our results therefore indicate that it may be possible to develop broad-spectrum inhibitors of Gram-negative PBP activation despite their use of diverse PBP regulators.