BINDING OF INFLUENZA-VIRUS HEMAGGLUTININ TO ANALOGS OF ITS CELL-SURFACE RECEPTOR, SIALIC-ACID - ANALYSIS BY PROTON NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY AND X-RAY CRYSTALLOGRAPHY
BINDING OF INFLUENZA-VIRUS HEMAGGLUTININ TO ANALOGS OF ITS CELL-SURFACE RECEPTOR, SIALIC-ACID - ANALYSIS BY PROTON NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY AND X-RAY CRYSTALLOGRAPHY
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DOI：
10.1021/bi00155a013
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发表时间：
1992-10-13
期刊：
影响因子：
2.9
通讯作者：
WILEY, DC
中科院分区：
文献类型：
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作者：
SAUTER, NK;HANSON, JE;WILEY, DC
通过合成12个唾液酸类似物，探讨了流感病毒血凝素与其细胞表面受体5-N-乙酰神经氨酸(唾液酸)的相互作用。这些唾液酸类似物包括2-羧酸、5-乙酰氨基、4-、7-和9-羟基以及糖苷位置上的衍生物。用核磁共振波谱测定了这些类似物的平衡离解常数。减少或取消结合的配体修饰包括用甲酰胺取代2-羧酸盐，用叠氮或N-苄氧基取代5-乙酰氨基，用氨基或O-乙酰基取代9-羟基。对结合影响不大的修饰包括在4-羟基位置引入更长的链，用乙基取代乙酰氨基甲基，以及去除7-羟基。X-射线衍射研究得到血凝素与四个合成类似物[α-2-O-甲基，4-O-乙酰基-α-2-O-甲基，9-氨基-9-脱氧-α-2-O-甲基-和alpha-2-O-(4‘-benzylamidocarboxybutyl)-N-acetylneuraminic酸]以及与天然存在的细胞表面糖(α2-3)唾液酸合成3角分辨晶体结构。X射线研究明确地确定了结合唾液酸的位置和方向，指出了(α2-3)唾液酸乳糖的乳糖基的位置，并提出了使唾液酸结合亲和力增加约3倍的α-糖苷链(4‘-苄基酰胺基羧丁基)的位置。尽管与α-2-O-甲基唾液酸结合的蛋白质在配体结合部位附近含有突变Gly-135->；Arg，但该突变显然不影响配体的位置。X射线研究使我们能够从晶体结构的角度解释结合亲和力。这些结果表明，进一步的实验可能导致设计具有可能治疗价值的紧密结合的抑制剂。
The interaction between influenza virus hemagglutinin and its cell-surface receptor, 5-N-acetylneuraminic acid (sialic acid), was probed by the synthesis of 12 sialic acid analogs, including derivatives at the 2-carboxylate,5-acetamido,4-,7-, and 9-hydroxyl, and glycosidic positions. The equilibrium dissociation constants of these analogs were determined by nuclear magnetic resonance spectroscopy. Ligand modifications that reduced or abolished binding included the replacement of the 2-carboxylate with a carboxamide, the substitution of azido or N-benzyloxycarbonyl groups for the 5-acetamido group, and the replacement of the 9-hydroxyl with amino or O-acetyl moieties. Modifications having little effect on binding included the introduction of longer chains at the 4-hydroxyl position, the replacement of the acetamido methyl group with an ethyl group, and the removal of the 7-hydroxyl group. X-ray diffraction studies yielded 3 angstrom resolution crystal structures of hemagglutinin in complex with four of the synthetic analogs [alpha-2-O-methyl-, 4-O-acetyl-alpha-2-O-methyl-, 9-amino-9-deoxy-alpha-2-O-methyl-, and alpha-2-O-(4'-benzylamidocarboxybutyl)-N-acetylneuraminic acid] and with the naturally occurring cell-surface saccharide (alpha2-3)sialyllactose. The X-ray studies unambiguously establish the position and orientation of bound sialic acid, indicate the position of the lactose group of (alpha2-3)sialyllactose, and suggest the location of an alpha-glycosidic chain (4'-benzylamidocarboxybutyl) that increases the binding affinity of sialic acid by a factor of about 3. Although the protein complexed with alpha-2-O-methylsialic acid contains the mutation Gly-135 --> Arg near the ligand binding site, the mutation apparently does not affect the ligand's position. The X-ray studies allow us to interpret the binding affinities in terms of the crystallographic structure. The results suggest further experiments which could lead to the design of tight binding inhibitors of possible therapeutic value.