Investigation of the structure of lipid A from Actinobacillus actinomycetemcomitans strain Y4 and human clinical isolate PO 1021-7.
The lipopolysaccharides of Actinobacillus actinomycetemcomitans strain Y4 and a human clinical isolate PO 1021-7 were examined by SDS/PAGE, deoxycholate/PAGE and mass spectrometry. PAGE analysis revealed an electrophoretic pattern similar to the SR-type lipopolysaccharide (LPS) of Salmonella. Deoxycholate/PAGE indicated the LPS of A. actinomycetemcomitans to consist of short sugar chains. Chemical analysis revealed the presence of thiobarbituric-acid-positive material (3-deoxy-D-manno-octulosonic acid equivalents) and four neutral sugars: glucose, galactose, D-glycero-D-manno-heptose and L-glycero-D-manno-heptose. Phosphate, glucosamine, glycine, and the fatty acids, 3-hydroxymyristic acid, myristic acid and palmitic acid, comprised the remainder of the molecule. The structure of the free lipid A revealed it to consist of a 1,6-glucosamine disaccharide esterified at C4' by a phosphomonoester. The hydroxyl group at C3 and the amide group of the non-reducing glucosamine were both acylated by 3-myristoylmyristic acid; analogous sites on the reducing glucosamine were acylated by 3-hydroxymyristic acid. Hydroxyl groups at C4 and C6' in the free lipid A were unsubstituted, with C6 being the proposed attachment site of the polysaccharide moiety. Chemical analysis revealed the presence of glycine in the intact LPS; its exact location in the A. actinomycetemcomitans LPS is still to be determined. Both intact LPS and free lipid A were highly lethal to galactosamine-sensitized mice, comparable to that of Salmonella.
Department of Periodontics, University of Texas Health Science Center, San Antonio 78284-7894.
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Masoud
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Wang
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D000188:Actinobacillus / Q000737:chemistry*; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D005227:Fatty Acids / Q000032:analysis; D005260:Female; D005690:Galactose / Q000032:analysis; D005947:Glucose / Q000032:analysis; D006539:Heptoses / Q000032:analysis; D008050:Lipid A / Q000032:analysis / Q000737:chemistry* / Q000633:toxicity; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008745:Methylation; D051379:Mice; D008810:Mice, Inbred C57BL; D015394:Molecular Structure; D013400:Sugar Acids / Q000032:analysis; D013858:Thiobarbiturates
D005227:Fatty Acids; D006539:Heptoses; D008050:Lipid A; D013400:Sugar Acids; D013858:Thiobarbiturates; C002532:2-keto-3-deoxyoctonate; C026312:glycero-manno-heptose; D005947:Glucose; C029684:thiobarbituric acid; D005690:Galactose