Structural characterization of the acid-degraded secondary cell wall polymer of Geobacillus stearothermophilus PV72/p2

The secondary cell wall polymer (SCWP) from Geobacillus stearothermophilus PV72/p2, which is involved in the anchoring of the surface-layer protein to the bacterial cell wall layer, is composed of 2-amino-2-deoxy- and 2-acetamido-2-deoxy-d-glucose, 2-acetamido-2-deoxy-d-mannose, and 2-acetamido-2-deoxy-d-mannuronic acid. The primary structure of the acid-degraded polysaccharide—liberated by HF-treatment from the cell wall—was determined by high-field NMR spectroscopy and mass spectrometry using N-acetylated and hydrolyzed polysaccharide derivatives as well as Smith-degradation. The polysaccharide was shown to consist of a tetrasaccharide repeating unit containing a pyruvic acid acetal at a side-chain 2-acetamido-2-deoxy-α-d-mannopyranosyl residue. Substoichiometric substitutions of the repeating unit were observed concerning the degree of N-acetylation of glucosamine residues and the presence of side-chain linked 2-acetamido-2-deoxy-β-d-glucopyranosyl units:Figure optionsDownload full-size imageDownload as PowerPoint slide

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