Salmonella enterica serovar Typhimurium lipopolysaccharide deacylation enhances its intracellular growth within macrophages

Modification of lipid A is essential for bacterial adaptation to its host. Salmonella Typhimurium LpxR potentially detoxifies lipid A by 3′-O-deacylation; however, the involvement of deacylation in its adaptation remains unclear. LpxR-dependent 3′-O-deacylation was observed in the stationary phase. When macrophages were infected with stationary phase bacteria, the intracellular growth of the lpxR-null strain was lower than that of the wild-type strain. Furthermore, the expression level of inducible nitric oxide synthase was higher in the cells infected with the lpxR-null strain than in the cells infected with the wild-type strain. These results indicate that lipid A 3′-O-deacylation is beneficial for intracellular growth.