Evidence Suggesting That Francisella tularensis O-Antigen Capsule Contains a Lipid A-Like Molecule That Is Structurally Distinct from the More Abundant Free Lipid A
Fig 1
Analysis of O-antigen capsule prepared according to Scheme A, (S1A Fig) SDS-PAGE/immunoblotting for O-Ag capsule (antibody 11B7).
The position of a 250 kD molecular weight standard is indicated. B) SDS-PAGE of metabolically labeled EtOHp and capsule, followed by immunoblot for Francisella O-antigen (clone FB11, left) or autoradiographic imaging (right). Denoted by asterisks are free lipid A (*), lipid A-core polysaccharide (no O-Ag) (**), and lipid A-core polysaccharide-single O-Ag unit (***) [16]. C) Distribution of cpm after chemical hydrolysis of EtOHp and capsule to release fatty acids. D) HPLC analysis of released [14C]-fatty acids from EtOHp and capsule extracted and recovered in the CHCl3 phase after chemical hydrolysis. Recovery of each individual fatty acid species is expressed as % of total recovery of [14C]lipids. Individual fatty acids were identified by comparison to commercial standards (C14:0, C16:0) or LC-MS analysis, as described previously [11].