Lipopolysaccharides possessing two L-glycero-D-manno-heptopyranosyl-α-(1→5)-3-deoxy-D-manno-oct-2-ulopyranosonic acid moieties in the core region -: The structure of the core region of the lipopolysaccharides from Burkholderia caryophylli

The carbohydrate backbone of the core-lipid A region was characterized from the lipopolysaccharides (LPSs) of the plant-pathogenic bacterium Burkholderia caryophylli. For the first time, the presence of two moieties of L-glycero-D-manno-heptopyranosyl-alpha-(1-->5)-3-deoxy-D-manno-oct-2-ulopyranosonic acid was identified in a core region, which is of particular interest with regard to the biosynthesis of this and of LPSs in general. The LPSs of B. caryophylli were degraded by mild hydrazinolysis (de-O-acylation), treatment with 48% aqueous HF at 4 degreesC (cleavage of phosphate groups and destruction of the O-specific polysaccharides), reduction with NaBH4, and de-N-acylation utilizing hot KOH. The major oligosaccharide representing the carbohydrate backbone of the core region and lipid A was isolated by high-performance anion-exchange chromatography. Its analysis employing compositional and methylation analyses, matrix-assisted laser desorption/ionization mass spectrometry, and H-1 and C-13 NMR spectroscopy applying various one-dimensional and two-dimensional experiments identified the following structure. [GRAPHICS] All sugars are pyranoses and alpha-linked, if not stated otherwise. Hep, is L-glycero-D-manno-heptose, Kdo is 3-de-oxy-D-manno-oct-2-ulosonic acid.