Structure and Biological Properties of the O-specific Polysaccharide and Lipid a from Pantoea agglomerans P324

Abstract

Lipopolysaccharide (LPS) of a new Pantoea agglomerans strain P324 was studied by chemical and biological methods. Mild acid hydrolysis of the LPS resulted in lipid A and O-specific polysaccharide (OPS) fractions. Studies by negative-ion mode HR ESI mass spectrometry showed heterogeneity of the lipid A, the major form being a hexa-acylated derivative containing biphosphorylated GlcN disaccharide, four 14:0 (3-OH), one 18:0, and one 12:0 residues. The following structure of the OPS was elucidated by chemical, NMR and computational methods: →3)-α-L-Rhap-(1→4)-α-D-Glcp-(1→. The P. agglomerans P324 LPS showed medium level of toxic and pyrogenic activities. Structural components of the LPS exhibited varying effects on the activity of Bacillus peptidases. Thus, the OPS and lipid A played a significant role in the hydrolysis of fibrin by Bacillus proteases but did not affect the activity of protease 2 of B. thuringiensis IMV B-7465 and protease 1 of B. thuringiensis IMV B-7324. Hydrolysis of elastin was intensified by core oligosaccharide and lipid A. Hydrolysis of collagen in the presence of the isolated fractions was accompanied by the inhibition of activity as compared to the native LPS.