Structural elucidation of theO-specific antigen ofYersinia ruckerii by fast atom bombardment mass spectrometry (FAB-MS)

Abstract

The precise molecular structure of the cell-surface lipopolysaccharide (LPS) of the gram-negative bacterium Yersinia ruckerii (Serovar 11) has been investigated. This bacterium is the causative agent of enteric redmouth disease in fish, a disease which constitutes an important economic problem in commercial rainbow trout hatcheries. We present in this letter positive ion fast atom bombardment mass spectral studies carried out on the 9-specific antigen, one of the distinct segments of the LPS and the portion containing the epitopes. chemical-ionization fragmentation) of the derived alditol acetates and of the acetylated derivatives of the methyl and the (-)-2-butyl glycosides, the 0-specific antigen was found to be composed of 2-acetamido-2,6-~ideoxy-~-glucose (N-acetyl-gquinovosamine), 2-acetamido-2-deoxy-~-glucose (N-acetyl-gglucosamine) and N-acetyl-q-muramic acid in the molar ratio of -1:l:l. The chemical structure of this 0-specific antigen was determined using sugar and methylation analyses, specific degradations, chromium trioxide oxidation and both 'H and 13C-nuclear magnetic resonance'. We have established that this -0-specific antigen was an unbranched linear heteropolymer, formed of a repeating trisaccharide unit and having the following structure:On the basis of combined GC-MS (electron-impact and OAc J. 6 [ 4 ) -a-g-MurpNAc--( 1-13) -a-D-QuipNAc--( 14)-BD-GlcpNAc---( 1-11It is well documented that mass spectrometry using surface ionization modes is a powerful technique for the structural investigation of complex carbohydrates2 and we have determined that positive ion FAB was the most suitable method for the analysis of this 0-specific polysaccharide.In effect, tLe fully permethylated 0-specific antigen gave an excellent positive ion FAB-MS that was easy to interpret and that contained complete sequence information. The major ions formed were derived from the single pathway A cleavage2, which occurred predominantly at each hexosaminal residue yielding a series of characteristic sequence-ions. determination is shown in the following Fig. 1 permethylated 0-specific antigen, we could recognize the major characteristic-sequence-ions originating from the complete native heteropolymer backbone (main series), in addition to two minor series (series I and 11) affording low abundance sequence-ions. These two minor sequences starting with QuiNAc as well as GlcNAc may well explain the phenomenon of microheterogeneity always associated with the incomplete biosynthesis of bacterial smooth lipopoly~accharide~.

Elucidation of the molecular structure of lipid A isolated from both a rough mutant and a wild strain of Aeromonas salmonicida lipopolysaccharides using electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

“…Glycosidic cleavages induced by MS and MS/MS provide useful structural information and sugar sequencing of complex carbohydrates 36–39. In conventional ESI‐MS, two distinctive ions at m/z 1074.7546 and 710.4271 were observed and were assigned as the [CH] − and [YH] − ions, respectively, and are shown in Scheme .…”

Structural investigation of bacterial lipopolysaccharides by mass spectrometry and tandem mass spectrometry

“…Some bacteria display shorter O-chains, on average, than others. The smooth-type Yersinia ruckerii serotype II is in this category (Banoub et al, 1990;Bateman, Banoub, & Thibault, 1996). In some cases the last sugar of the O-chain (non-reducing end) carries a substituent blocking the addition of subunits as a terminal signal.…”

Structure of the O-specific polysaccharide ofProteus penneristrain 41 from a new proposed serogroup O62

“…2) which, to the best of our knowledge, has not been found in any other polysaccharide. N ‐acetylmuramic acid commonly known as a component of bacterial cell‐wall peptidoglycan [27], has been found in the O‐specific polysaccharide of Yersinia ruckerii [28], whereas another isomer of N ‐acetylmuramic acid, 2‐acetamido‐3‐ O ‐[( S )‐1‐carboxyethyl]‐2‐deoxy‐ d ‐glucose ( N ‐acetylisomuramic acid), was reported in the O‐antigens of a number of other P. penneri strains [11, 21].…”