Structure of the O-polysaccharide of the lipopolysaccharide of Pseudomonas chlororaphis subsp. aureofaciens UCM B-306

• O-polysaccharide of P. chlororaphis subsp. aureofaciens B-306 was studied.
• The structure of the trisaccharide repeat of the polysaccharide was established.
• d-GalNAcA residue is non-stoichiometrically amidated (∼40%).

Structure of the O-specific polysaccharide from Pseudomonas chlororaphis subsp. aureofaciens UCM B-306 was elucidated by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy. The polysaccharide is built up of trisaccharide repeats containing d-rhamnose, 2,4-diacetamido-2,4,6-trideoxy-d-glucose (d-QuiNAc4NAc), and 2-acetamido-2-deoxy-d-galacturonic acid (d-GalNAcA), which is amidated in ∼40% repeats. It was suggested that the O-polysaccharide has a blockwise structure, which can be presented as follows:-[→3)-α-d-Rhap-(1→4)-α-d-GalpNAcA-(1→3)-α-d-QuipNAc4NAc-(1-]n→ and -[→3)-α-d-Rhap-(1→4)-α-d-GalpNAcAN-(1→3)-α-d-QuipNAc4NAc-(1-]m→, where GalNAcAN indicates 2-acetamido-2-deoxy-d-galacturonamide, n:m=∼3:2.

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