Structure of the O-polysaccharide chain of the lipopolysaccharide of Vibrio anguillarum V-123

Abstract

The O-polysaccharide chain (PS-1), released by mild acidic treatment of the LPS of V. anguillarum V-123 (serogroup JO-2), pathogenic bacterium of marine and estuarine fish, consists of 2-amino-2-deoxy- d-galacturonic acid, 2-amino-2,6-dideoxy- d-glucose ( d-quinovosamine), and 4-amino-4,6-dideoxy- d-glucose ( d-viosamine) N-acylated with 2,4-dihydroxy-3,3,4-trimethylpyroglutamic acid. Strong-acid hydrolysis of PS-1 afforded α-GalNA-(1 → 4)-α-GalNA-(1 → 3)-QuiN (A1) and α-GalNA-(1 → 3)-QuiN (A2), and hydrolysis with hydrogen fluoride gave N-acetylated A1 and 4-amino-4,6-dideoxy- d-glucose N-acylated by 2,4-dihydroxy-3,3,4-trimethylpyroglutamic acid. Mild treatment of PS-1 with alkali removed the N-formyl substituents and Smith degradation of the product gave α-QuiNAc-(1 → 3)-β-VioNAcyl-(1 → 3)-α-GalNAcA-(1 → 3)-2,3,4-trihydroxybutanoic acid (S1) and S2 in which the carboxyl group of the GalNAcA residue was amidated. Thus, the repeating unit of the O-polysaccharide is → 3)-α-GalNAcA(amido)-(1 → 4)-α-GalNFoA-(1 → 3)-α-QuiNAc-(1 → 3)-β-VioNAcyl-(1 → in which the N-Acyl group is 2,4-dihydroxy-3,3,4-trimethylpyroglutamic acid and Fo is formyl.