Risberg A, Masoud H, Martin A, Richards J C, Moxon E R, Schweda E K
Clinical Research Centre, Karolinska Institue, University College of South Stockholm, Huddinge, Sweden.
Eur J Biochem. 1999 Apr;261(1):171-80. doi: 10.1046/j.1432-1327.1999.00248.x.
Structural elucidation of the lipopolysaccharide (LPS) of Haemophilus influenzae, strain Rd, a capsule-deficient type d strain, has been achieved by using high-field NMR techniques and electrospray ionization-mass spectrometry (ESI-MS) on delipidated LPS and core oligosaccharide samples. It was found that this organism expresses heterogeneous populations of LPS of which the oligosaccharide (OS) epitopes are subject to phase variation. ESI-MS of O-deacylated LPS revealed a series of related structures differing in the number of hexose residues linked to a conserved inner-core element, L-alpha-D-Hepp-(1-->2)-L-alpha-D-Hepp-(1-->3)-[beta-D-Glcp- (1-->4)-]- L-alpha-D-Hepp-(1-->5)-alpha-Kdo, and the degree of phosphorylation. The structures of the major LPS glycoforms containing three (two Glc and one Gal), four (two Glc and two Gal) and five (two Glc, two Gal and one GalNAc) hexoses were substituted by both phosphocholine (PCho) and phosphoethanolamine (PEtn) and were determined in detail. In the major glycoform, Hex3, a lactose unit, beta-D-Galp-(1-->4)-beta-D-Glcp, is attached at the O-2 position of the terminal heptose of the inner-core element. The Hex4 glycoform contains the PK epitope, alpha-D-Galp-(1-->4)-beta-D-Galp-(1-->4)-beta-D-Glcp while in the Hex5 glycoform, this OS is elongated by the addition of a terminal beta-D-GalpNAc residue, giving the P antigen, beta-D-GalpNAc-(1-->3)-alpha-D-Galp-(1-->4)-beta-D-Galp-(1-->4)-D-Glc p. The fully extended LPS glycoform (Hex5) has the following structure. [see text] The structural data provide the first definitive evidence demonstrating the expression of a globotetraose OS epitope, the P antigen, in LPS of H. influenzae. It is noteworthy that the molecular environment in which PCho units are found differs from that observed in an Rd- derived mutant strain (RM.118-28) [Risberg, A., Schweda, E. K. H. & Jansson, P-E. (1997) Eur. J. Biochem. 243, 701-707].
通过对去脂脂多糖（LPS）和核心寡糖样品运用高场核磁共振技术及电喷雾电离质谱（ESI-MS），已完成对流感嗜血杆菌Rd菌株（一种d型无荚膜菌株）LPS的结构解析。研究发现，该菌表达的LPS群体具有异质性，其寡糖（OS）表位会发生相变。O-脱酰基LPS的ESI-MS显示出一系列相关结构，这些结构在与保守内核元件相连的己糖残基数量、L-α-D-庚糖-（1→2）-L-α-D-庚糖-（1→3）-[β-D-葡萄糖-（1→4）-]-L-α-D-庚糖-（1→5）-α-Kdo以及磷酸化程度上存在差异。对含有三个（两个葡萄糖和一个半乳糖）、四个（两个葡萄糖和两个半乳糖）和五个（两个葡萄糖、两个半乳糖和一个N-乙酰半乳糖胺）己糖的主要LPS糖型结构进行了详细测定，这些糖型均被磷酸胆碱（PCho）和磷酸乙醇胺（PEtn）取代。在主要糖型Hex3中，一个乳糖单元β-D-半乳糖-（1→4）-β-D-葡萄糖连接在内核元件末端庚糖的O-2位。Hex4糖型包含PK表位α-D-半乳糖-（1→4）-β-D-半乳糖-（1→4）-β-D-葡萄糖，而在Hex5糖型中，该OS通过添加一个末端β-D-N-乙酰半乳糖胺残基得以延长，形成P抗原β-D-N-乙酰半乳糖胺-（1→3）-α-D-半乳糖-（1→4）-β-D-半乳糖-（1→
