The surface layer (S-layer) glycoprotein of Geobacillus stearothermophilus NRS 2004/3a. Analysis of its glycosylation

Isolation of glucocardiolipins from Geobacillus stearothermophilus NRS 2004/3a

Glucose-substituted cardiolipins account for about 4 mol% of total phospholipid extracted from exponentially grown cells of Geobacillus stearothermophilus NRS 2004/3a. Individual glucocardiolipin species exhibited differences in fatty acid substitution, with iso-C(15:0) and anteiso-C(17:0) prevailing. The compounds were purified to homogeneity by a novel protocol and precharacterized by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

The structures of the lipooligosaccharide and capsule polysaccharide of Campylobacter jejuni genome sequenced strain NCTC 11168

Campylobacter jejuni infections are one of the leading causes of human gastroenteritis and are suspected of being a precursor to Guillain-Barré and Miller-Fisher syndromes. Recently, the complete genome sequence of C. jejuni NCTC 11168 was described. In this study, the molecular structure of the lipooligosaccharide and capsular polysaccharide of C. jejuni NCTC 11168 was investigated. The lipooligosaccharide was shown to exhibit carbohydrate structures analogous to the GM1a and GM2 carbohydrate epitopes of human gangliosides (shown below): The high Mr capsule polysaccharide was composed of beta-d-Ribp, beta-d-GalfNAc, alpha-d-GlcpA6(NGro), a uronic acid amidated with 2-amino-2-deoxyglycerol at C-6, and 6-O-methyl-d-glycero-alpha-l-gluco-heptopyranose as a side-branch (shown below): The structural information presented here will aid in the identification and characterization of specific enzymes that are involved in the biosynthesis of these structures and may lead to the discovery of potential therapeutic targets. In addition, the correlation of carbohydrate structure with gene complement will aid in the elucidation of the role of these surface carbohydrates in C. jejuni pathogenesis.

Mapping and sequencing of cardiolipins from Geobacillus stearothermophilus NRS 2004/3a by positive and negative ion nanoESI-QTOF-MS and MS/MS

In the course of systematic studies on surface layer (S-layer) glycoproteins of bacilli, the chloroform/methanol extract from whole cells of Geobacillus stearothermophilus NRS 2004/3a has been submitted to MS analysis. Glucosylated cardiolipins were found as minor components of the total lipid and phospholipid mixture by de novo identification. After purification of the crude extract using a combined column chromatography/2D TLC protocol, structural investigations of components in the lipid fraction by high resolution ESI-QTOF MS analysis provided evidence about homologous molecules attributable to the cardiolipin species containing a glycosylated backbone, and about a diversity of ester-linked fatty acid substituents. In comparative studies by positive and negative ion nanoESI-QTOF-CID-MS, maps of cardiolipin molecular ions were obtained, followed by MS/MS of the most abundant species, to provide structural details of D-glucopyranosylcardiolipin and the fatty acid substituent patterns. Experiments of the parent ion scan type revealed the presence of fatty acid moieties as isobaric combinations, represented in single molecular ion species.