Rahman M M, Stephens D S, Kahler C M, Glushka J, Carlson R W
Complex Carbohydrate Research Center, University of Georgia, Athens 30602, USA.
Carbohydr Res. 1998 Feb;307(3-4):311-24. doi: 10.1016/s0008-6215(98)00012-3.
The complete structure of the lipooligosaccharide (LOS) from Neisseria meningitidis strain NMB (serotype 2b:P1.2,5), a serogroup B cerebrospinal fluid isolate, was determined. Two oligosaccharide (OS) fractions and lipid-A were obtained following mild acid hydrolysis of the LOS. The structures in these fractions were determined using glycosyl composition and linkage analyses, N spectroscopy and mass spectrometry. One oligosaccharide fraction (OS1) consists of a molecule having a glycosyl sequence identical to that previously reported for the LOS from immunotype L2 N. meningitidis [A. Gamain, M. Beurret, F. Michon, J.-R. Brisson, and H.J. Jennings, J. Biol. Chem.,267,(112) 922-925] i.e., a lacto-N-neotetraose is attached to heptose I (Hep I), with terminally linked N-acetylglucosaminosyl and glucosyl residues attached to Hep II of the inner core. Approximately 70% of this structure is acetylated at O-6 of the terminally linked alpha-N-acetyl-glucosaminosyl residue. As with the L2 structure, the NMB LOS contained phosphoethanolamine (PEA) at O-6 or O-7 of the Hep II residue. The second oligosaccharide fraction (OS2) contains a a mixture of three different molecules, all of which vary from one another in their glycosyl substitution patterns of the Hep II residue. The most abundant molecule in OS2 has a structure identical to that of OSI, i.e., it has the L2 glycosyl sequence. A second molecule (OS2a) lacks the terminal glucosyl residue at O-3 of Hep II; i.e., it has a glycosyl sequence identical to that of the mild acid released oligosaccharide of N. meningitidis immunotype L3, L4, or L7 LOSs. The third molecule (OS2b) is a novel structure that lacks the terminal N-acetylglucosaminosyl residue linked to O-2 of Hep II. Overall, 76% of OS released from NMB LOS has the L2 structure, 15% is OS2a (L3), and 9% is OS2b. A portion (20%) of the molecules in the NMB LOS preparation also contained terminally linked sialic acid attached to O-3 of the lacto-N-neotetraose galactosyl residue, which is also consistent with the L3, or L4 LOS structures. In contrast to the previously reported structure of N. meningitidis lipid-A [V. A. Kulshin, U. Zähringer, B. Linder, C.E. Frasch, C-M. Tsai, B.A. Dmitriev, and E.T Rietschel, J. Bacteriol., 174, (1992)1793-1800], only 30% of the lipid-A from NMB LOS possesses 4'-phosphate. Comparison with the lipid-A of LOS purified from an isogenic acapsulate mutant, M7, revealed that the 4'-position was almost completely occupied with phosphate. These data emphasize the structural heterogeneity of the OS and phosphate substituents of Hep II, and 4'-phosphorylation of lipid-A of meningococcal LOS.
确定了来自脑膜炎奈瑟菌菌株NMB（血清型2b：P1.2,5）的脂寡糖（LOS）的完整结构，该菌株是B群脑脊液分离株。对LOS进行温和酸水解后，得到了两个寡糖（OS）组分和脂质A。使用糖基组成和连接分析、N光谱和质谱确定了这些组分中的结构。一个寡糖组分（OS1）由一个糖基序列与先前报道的免疫型L2脑膜炎奈瑟菌的LOS相同的分子组成[A. Gamain、M. Beurret、F. Michon、J.-R. Brisson和H.J. Jennings，《生物化学杂志》，267，(112) 922 - 925]，即乳糖-N-新四糖连接到庚糖I（Hep I）上，末端连接的N-乙酰葡糖胺基和葡糖基残基连接到内核的Hep II上。该结构中约70%在末端连接的α-N-乙酰葡糖胺基残基的O-6位被乙酰化。与L2结构一样，NMB LOS在Hep II残基的O-6或O-7位含有磷酸乙醇胺（PEA）。第二个寡糖组分（OS2）包含三种不同分子的混合物，它们在Hep II残基的糖基取代模式上彼此不同。OS2中最丰富的分子具有与OSI相同的结构，即它具有L2糖基序列。第二个分子（OS2a）在Hep II的O-3位缺少末端葡糖基残基；即它具有与脑膜炎奈瑟菌免疫型L3、L4或L7 LOS的温和酸释放寡糖相同的糖基序列。第三个分子（OS2b）是一种新结构，缺少连接到Hep II的O-2位的末端N-乙酰葡糖胺基残基。总体而言，从NMB LOS释放的OS中76%具有L2结构，15%是OS2a（L3），9%是OS2b。NMB LOS制剂中的一部分（20%）分子还在乳糖-N-新四糖半乳糖基残基的O-3位含有末端连接的唾液酸，这也与L3或L4 LOS结构一致。与先前报道的脑膜炎奈瑟菌脂质A的结构[V. A. Kulshin、U. Zähringer、B. Linder、C.E. Frasch、C-M. Tsai、B.A. Dmitriev和E.T Rietschel，《细菌学杂志》，174，(1992)1793 - 1800]相比，NMB LOS的脂质A中只有30%具有4'-磷酸。与从同基因无荚膜突变体M7纯化的LOS的脂质A比较表明，4'-位几乎完全被磷酸占据。这些数据强调了OS和Hep II的磷酸取代基的结构异质性以及脑膜炎球菌LOS脂质A的4'-磷酸化。
