Pant, I.; Ravindranath, S.; Potnis, A. A.

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.