Gene knockout studies of Dps protein reveals a novel role for DNA-binding protein in maintaining outer membrane permeability

Abstract

DNA-binding proteins like Dps are crucial for bacterial stress physiology. This study investigated the unexpected role of Dps protein in maintaining outer membrane integrity of Salmonella Typhimurium. We observed that a{Delta} dps mutant displayed increased sensitivity to glycopeptide antibiotics (vancomycin, nisin), which are ineffective against Gram-negative bacteria due to their thick outer membrane (OM). Furthermore, the{Delta} dps mutant exhibited susceptibility to membrane-disrupting agents like detergents (deoxycholate, SDS) and phages. The perforation was observed in OM after the treatment of vancomycin using atomic force microscopy (AFM). Notably, this sensitivity was rescued by supplementing the media with calcium and magnesium cations. These findings suggest a novel function for Dps in maintaining outer membrane permeability. We propose two potential mechanisms: 1) Dps might directly localize to the outer membrane, or 2) Dps might regulate genes responsible for lipopolysaccharide (LPS) synthesis or outer membrane proteins, key components of outer membrane. This study highlights a previously unknown role for Dps beyond DNA binding and warrants further investigation into the precise mechanism by which it influences outer membrane integrity in Salmonella. IMPORTANCELarge, hydrophilic glycopeptides like vancomycin are ineffective against Gram-negative bacteria due to their inability to penetrate thick outer membrane of the Gram-negative bacteria. This study investigates the role of the DNA-binding protein, Dps, in maintaining outer membrane integrity. We demonstrate that Dps loss renders bacteria susceptible to vancomycin. These findings suggest Dps as a potential target for developing novel therapeutic strategies, potentially involving combinations with glycopeptide antibiotics, to combat resistant against Gram-negative pathogens.