Figure 1.

(A) Structure diagram of P. gingivalis-LPS. LPS is composed of lipid A (the conserved inner region without species specificity), core oligosaccharide (the bridge between lipid A and O-polysaccharide), and O-specific polysaccharide (a highly variable outer region) and located on bacterial outer membrane. (B) Contrast different acylation structure of P. gingivalis and E. coli LPS. Lipid A is composed of a phosphorylated β (1-6) D-glucosamine disaccharide backbone and multi-acyl chains acylated by fatty acids at specific positions. P. gingivalis-LPS with tetra-acylated chains is designated as LPS_1435/1449 with its molecular weight of 1435 and 1449 Da, while the penta-acylated is named P. gingivalis-LPS₁₆₉₀ with a molecular weight of 1690 Da. The lipid A of E. coli-LPS is hexa-acylated.