Note Structural analysis of the core oligosaccharide from Pasteurella multocida strain X73 Frank St. Michael, Jianjun Li and Andrew D. Cox * Institute for Biological Sciences, 100 Sussex Drive, National Research Council, Ottawa, ON, Canada K1A 0R6 Received 21 October 2004; accepted 15 February 2005 Abstract—The structure of the core oligosaccharide region of the lipopolysaccharide from the Pasteurella multocida strain X73 was elucidated. The lipopolysaccharide was subjected to a variety of degradative procedures. The structure of the purified oligosaccha- ridewasestablishedbymonosaccharideandmethylationanalyses,NMRspectroscopyandmassspectrometry.Thefollowingstruc- ture illustrates a similar structure to the recently identified oligosaccharide from another P. multocida strain VP161, but with additional symmetrical substitution of the terminal galactose residues with phosphoethanolamine moieties, α-Glc II 6 -(1 5)- -Kdo α 1 LD ,-- α Hep II LD ,-- α Hep III 2 1 3 | | LD ,-- α Hep I β-Gal -(1 6)- I 3 PCho PEtn PEtn 6 6 I I II β-Gal II 4 3 PCho II β-Glc -(1 4)- I LD , - -Hep -(1 6)- α IV where based on the NMR data all sugars were found in pyranose ring forms and Kdo is 3-deoxy-a-D-manno-2-oct-2-ulosonic acid, L,D-a-Hep is L-glycero-D-manno-heptose, PEtn is phosphoethanolamine and PCho is phosphocholine. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Pasteurella multocida; LPS; Core oligosaccharide; Mass spectrometry; NMR Pasteurella multocida (Pm) is a Gram-negative bacte- rium and multi-species pathogen that causes serious dis- eases in food animals and humans. 1 Structural analyses on the lipopolysaccharide (LPS) of the genome strain Pm70 2 and a virulent serotype A:1 strain VP161 3 have revealed a conserved inner core oligosaccharide (OS) structure with variable outer core OS structures. This study was carried out on another virulent serotype A strain X73 and structural analysis of the purified LPS products revealed a similar OS structure to that found for strain VP161 but with an additional symmetrical phosphorylation pattern to the outer core OS. Sugar analysisofthepurifiedLPSand8Kpelletmaterialfrom strain X73 revealed a similar profile to strain VP161 containing the sugars glucose (Glc), galactose (Gal) and L-glycero-D-manno-heptose (LD LD-Hep)intheapprox- imate ratio of 2:1:4, respectively. O-Deacylated LPS (LPS-OH) was prepared from fermenter-grown cells and analysed by CE–MS (Table 1). A similar mass pro- file to that observed for strain VP161 was observed, but 0008-6215/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.carres.2005.02.014 * Corresponding author. Tel.: +1 613 991 6172; fax: +1 613 952 9092; e-mail: andrew.cox@nrc-cnrc.gc.ca Carbohydrate RESEARCH Carbohydrate Research 340 (2005) 1253–1257