STRUCTURAL ELUCIDATION OF THE LIPOPOLYSACCHARIDE CORE REGIONS OF THE WILD-TYPE STRAIN PAO1 AND O-CHAIN-DEFICIENT MUTANT STRAINS AK1401 AND AK1012 FROM PSEUDOMONAS-AERUGINOSA SEROTYPE O5

Lipopolysaccharide (LPS) of the Pseudomonas aeruginosa serotype O5 wil d-type strain PAO1 and derived rough-type mutant strains AK1401 and AK 1012 was isolated by a modified phenol/chloroform/ petroleum-ether ext raction method. Deoxycholate/PAGE of the LPS from the rough mutant AK1 401 indicated two bands near the dye front with mobilities similar to those of the parent strain, indicating that both LPS contain a complet e core and a species comprising a core and one repeating unit. Composi tion analysis of the LPS from strains PAO1 and AK1401 indicated that t he complete core oligosaccharide was composed of D-glucose (four units ), L-rhamnose tone unit), 2-amino-2-deoxy-D-galactose tone unit), L-gl ycero-D-manno-heptose (Hep; two units), 3-deoxy-D-manno-octulosonic ac id (Kdo; two units), L-alanine tone unit) and phosphate (three units). The glycan structure of the LPS was determined by one-dimensional and two-dimensional (2D) NMR techniques in combination with MS-based meth ods on oligosaccharide samples obtained from the LPS by delipidation p rocedures. The locations of three phosphomonoester groups on the first heptose residue were established by a two-dimensional P-31 (omega(1)) -half-filtered COSY experiment on the reduced core oligosaccharide sam ple of the LPS from the wild-type strain. The presence of a 7 O-carbam oyl substituent was observed on the second heptose. The structure of t he core region of the O-chain-deficient LPS from P. aeruginosa serotyp e O5 is as follows: [GRAPHICS] where R-1 is cp-(1-->2)-alpha-L-Rhap-(1 -->6)-alpha-D-Glcp-(1--> and R-2 is alpha-D-Glcp-(1-->6)-beta-D-Glcp-( 1-->. A structural model is presented that is also representative of t hat for P. aeruginosa serotype O6 LPS. A revised structure for the ser otype O6 mutant strain A28 is presented.