Mode of action of GR69153, a novel catechol-substituted cephalosporin, and its interaction with the tonB-dependent iron transport system

GR69153 is a novel cephalosporin incorporating a catechol-substituted 7-aminothiazolyl-oxime. The antibiotic is actively transported into gram-negative cells via iron-regulated outer membrane proteins regulated by the tonB product. This transport enhances bactericidal activity most significantly at low concentrations, essentially removing the permeability barrier for antibiotic uptake.