Structure of lipid A from a stem-nodulating bacterium Azorhizobium caulinodans

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• 作者：Adam Choma^a ; ^{adam.choma@poczta.umcs.lublin.pl} ; Iwona Komaniecka^a ; Anna Turska-Szewczuk^a ; Witold Danikiewicz^b ; Grzegorz Spolnik^b
• 关键词：2 ; 3-Diamino-2 ; 3-dideoxyglucose ; Azorhizobium ; Glucuronic acid ; Lipopolysaccharide ; Lipid A ; Fatty acid distribution
• 刊名：Carbohydrate Research
• 出版年：2012
• 期刊代码：15_00086215
• 类别：ch
• 出版时间：1 May, 2012
• 卷：352
• 期：Complete
• 页码：126-136
• 文件大小：732 K

摘要

The structure of the lipid A of the lipopolysaccharide (LPS) from Azorhizobium caulinodans, a symbiont of the tropical legume Sesbania rostrata, was investigated by chemical compositional analyses, mass spectrometry, as well as 1D and 2D NMR spectroscopy techniques. The lipid A backbone was composed of a 尾-(1鈫?)-linked 2,3-diamino-2,3-dideoxy-d-glucopyranose (GlcpN3N) disaccharide and 伪-d-glucuronic acid (GlcpA). Nuclear magnetic resonance spectroscopy revealed that the GlcpA was connected to the reducing end of the diaminosugar disaccharide via an 伪-(1鈫?) glycosidic bond. The lipid A was deprived of phosphate residues. ESI-MS analysis showed that the lipid A preparation was a mixture of molecules due to the occurrence of different acylation patterns. The GlcpN3N disaccharide backbone was N-acylated at the C-2, C-3, C-2鈥?and C-3鈥?positions with 3-OH-18:0, 3-OH-14:0, 3-OH-20:1 and 3-OH-14:0 fatty acids, respectively. Nonpolar fatty acids as well as 3-OH-18:0 were found to be ester-linked. They were attached to hydroxyl groups of primary 3-OH fatty acids giving three acyloxyacyl moieties. Thus, the complete lipid A from A. caulinodans comprised seven acyl residues. Part of the lipid A molecules was esterified by 3-methoxybutyric acid. Azorhizobium caulinodans did not incorporate 蠅-1 hydroxylated very long chain fatty acids (e.g., 27-OH-28:0) into the lipid A, which makes this variant of endotoxin unusual among rhizobial lipids A.