Identification of the Salmonella enterica damX Gene Product, an Inner Membrane Protein Involved in Bile Resistance

The damX gene product of Salmonella enterica serovar Typhimurium is a protein located in the inner membrane. DamX migrates as a 70-kDa protein in SDS-PAGE even though the predicted protein size is 46 kDa. Synthesis of DamX protein occurs in both exponential- and stationary-phase cultures. Disruption of damX causes severe sensitivity to bile. Lack of the outer membrane protein AsmA suppresses bile sensitivity in Salmonella damX mutants.