Structure of the lipid A–inner core region and biological activity of Plesiomonas

Plesiomonas shigelloides is a Gram-negative rod associ-ated with episodes of intestinal infections and outbreaks of diarrhea in humans. The extraintestinal infections caused by this bacterium, for example, endopthalmitis, meningitidis, bacteremia, and septicemia, usually have gastrointestinal origin and serious course. The lipopolysaccharide (LPS, endotoxin) as virulence factor is important in enteropatho-genicity of this bacterium. LPSs of P. shigelloides and especially their lipid A part, that is, the immunomodula-tory center of LPS, have not been extensively investigated. The structure of P. shigelloides O54 lipid A was deter-mined by chemical analysis combined with MALDI-TOF mass spectrometry, and the intact Kdo-containing core region was investigated by NMR spectroscopy on deacy-lated LPS. Products from alkaline deacylation of LPS