Institute of Molecular Biology and Genetics, Interdisciplinary Program for Biochemical Engineering and Biotechnology, Seoul National University, Seoul 151-742, Republic of Korea.
Biochem Biophys Res Commun. 2011 Apr 22;407(4):823-30. doi: 10.1016/j.bbrc.2011.03.107. Epub 2011 Apr 2.
Lipoteichoic acid is a major cell wall virulence factor of gram-positive bacteria. LTAs from various bacteria have differential immunostimulatory potentials due to heterogeneity in their structures. Although recent studies have demonstrated that LTA isolated from Lactobacillus plantarum (pLTA) has anti-inflammatory properties and is less inflammatory than LTAs from pathogenic bacteria, little is known about the structure of pLTA. In this study, high-field NMR spectra of the pLTA were compared with those of LTA from pathogenic bacterium, Staphylococcus aureus (aLTA). The 2D NMR results demonstrated that pLTA possesses α-linked hexose sugar substituents on the poly-glycerophosphate backbone instead of N-acetylglucosamine substituents, and unsaturated fatty acids in its glycolipids. The sugar substituents were revealed as an approximately 29:1 molar ratio of the glucose to galactose by HPAEC-PAD analysis. MALDI-TOF/TOF MS analyses identified the presence of unsaturated fatty acids in the glycolipid moieties of pLTA. In addition, the glycolipid structure was found to be composed of trihexosyl-diacyl- and/or trihexosyl-triacyl-glycerol ceramide units by means of unique fragment ions of the glycolipids. These results enabled us to elucidate the pLTA structure, which is distinctively different from canonical LTA structure, and suggest that the unique immunological property of pLTA might be caused by the pLTA structure.
脂磷壁酸是革兰氏阳性菌的主要细胞壁毒力因子。由于结构的异质性，来自不同细菌的 LTAs 具有不同的免疫刺激潜力。尽管最近的研究表明，来自植物乳杆菌（pLTA）的 LTA 具有抗炎特性，并且比来自病原菌的 LTAs 的炎症反应性低，但对于 pLTA 的结构知之甚少。在这项研究中，比较了 pLTA 的高场 NMR 谱与病原菌金黄色葡萄球菌（aLTA）的 LTA 的 NMR 谱。2D NMR 结果表明，pLTA 在聚甘油磷酸骨架上具有α-连接的己糖取代基而不是 N-乙酰葡萄糖胺取代基，并且其糖脂中存在不饱和脂肪酸。通过 HPAEC-PAD 分析，糖取代基的葡萄糖与半乳糖摩尔比约为 29:1。MALDI-TOF/TOF MS 分析鉴定了 pLTA 糖脂部分存在不饱和脂肪酸。此外，通过糖脂的独特碎片离子，发现糖脂结构由三己糖二酰基-和/或三己糖三酰基甘油神经酰胺单元组成。这些结果使我们能够阐明 pLTA 的结构，该结构与典型的 LTA 结构明显不同，并表明 pLTA 的独特免疫特性可能是由 pLTA 的结构引起的。
