[Outer membrane remodeling of Salmonella typhimurium and host innate immunity].
Pathogenic gram-negative bacteria, including Salmonella typhimurium, remodel their outer membrane to survive within host tissues and phagosomes. The remodeling includes modifications of lipid A, a membrane anchor portion of lipopolysaccharide. Lipid A modifications, such as palmitoylation, deacylation, addition of aminoarabinose, and addition of phosphoethanolamine, are beneficial for salmonellae to resist host innate immunity. Aminoarabinose attachment, phosphoethanolamine attachment, and palmitoylation of lipid A increase salmonellae resistance to cationic antimicrobial peptides. Lipid A deacylation and palmitoylation reduce its ability to activate the Toll-like receptor 4-MD-2 complex, suggesting that these modifications are beneficial for salmonellae to evade host innate immune recognition. These modifications are regulated transcriptionally by the two-component regulatory system PhoP-PhoQ, which is essential for S. typhimurium virulence. Lipid A modifications are also regulated posttranslationally. Aminoarabinose modification of lipid A represses deacylation of lipid A by PagL. The posttranslational regulation may be involved in S. typhimurium pathogenesis.
Kawasaki
Kiyoshi
K
Faculty of Pharmaceutical Sciences, Doshisha Women's College, Kyoto, Japan. kkawasak@dwc.doshisha.ac.jp
D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000502:physiology; D001426:Bacterial Proteins / Q000502:physiology; D007113:Immunity, Innate / Q000276:immunology*; D008050:Lipid A / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D051197:Toll-Like Receptor 4 / Q000276:immunology; D014774:Virulence / Q000235:genetics
D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D008050:Lipid A; D008070:Lipopolysaccharides; D008563:Membrane Lipids; C079792:PhoQ protein, Bacteria; D051197:Toll-Like Receptor 4; C061064:PhoP protein, Bacteria