Structure of the Polysaccharide Moiety of the Klebsiella O3 Lipopolysaccharide Isolated from Culture Supernatant of Decapsulated Mutant (Klebsiella O3 : K1^-)

Abstract

In our earlier studies, the Klebsiella O3 lipopolysaccharide (LPS) isolated from culture supernatant of Klebsiella pneumoniae strain Kasuya (O3 : K1) or its decapsulated mutant strain LEN-1 (O3 : K1^-) was shown to exhibit a much stronger adjuvant effect than other known adjuvants, including LPS of Escherichia coli and Salmonella. The O3 LPS isolated from culture supernatant of Klebsiella strain LEN-1 was degraded into 59-66% neutral sugars and 25-27% lipids by hydrolysis with 1% acetic acid at 100°C for 1 h. The polysaccharide moiety (OPS) obtained by the hydrolysis was homogeneous on gel filtration. It contained 92.4% mannose, 0.15% 2-keto-3-deoxyoctonate and less than 0.1% P. The molecular weight values of OPS determined by gel filtration analysis and by the Somogyi-Nelson method were 14000 and 16200, respectively. The specific rotation of OPS was +88° and its infrared spectrum showed no β-configuration of mannopyranose. Methylation analysis indicated that OPS contained (1→2)-and (1→3)-linkages in a ratio of 3 : 2. Smith degradation and partial acid hydrolysis of OPS liberated mannosyl-(1→3)-mannose. We postulate that OPS consists of a mannan which has α-mannosyl-(1→3)-α-mannosyl-(1→2)-α-mannosyl-(1→2)-α-mannosyl-(1→2)-α-mannose units joined through α-mannosyl-(1→3)-linkages.