Structural basis for the recognition and cleavage of polysialic acid by the bacteriophage K1F tailspike protein EndoNF.
Structural basis for the recognition and cleavage of polysialic acid by the bacteriophage K1F tailspike protein EndoNF.
复制标题
DOI：
10.1016/j.jmb.2010.01.028
复制
发表时间：
2010-03
影响因子：
5.6
通讯作者：
E. Schulz;David Schwarzer;M. Frank;Katharina Stummeyer;M. Mühlenhoff;A. Dickmanns;R. Gerardy-Schahn;R. Ficner
中科院分区：
文献类型：
--
作者：
E. Schulz;David Schwarzer;M. Frank;Katharina Stummeyer;M. Mühlenhoff;A. Dickmanns;R. Gerardy-Schahn;R. Ficner
α-2，8-连接聚唾液酸(PolySIA)胶囊对神经侵袭性致病原核生物(如大肠杆菌K1和脑膜炎奈瑟菌)具有免疫耐受性，并通过分子模拟支持宿主感染。感染E.ColiK1的K1家族噬菌体利用尾钉内脂酶特异性地识别和降解这种多聚唾液酸囊膜。虽然噬菌体K1F的内唾液酸酶催化区的晶体结构已被解决，但关于PolySia结合和切割方式的结构信息尚不清楚。与低聚唾液酸共结晶的高三聚体内源性神经营养因子活性位点突变体的晶体结构表明，每个内源性神经营养因子单体中有三个独立的PolySia结合位点。结合的寡聚唾液酸在每个位置显示不同的构象。在活性部位，Sia3分子结合在代表酶-产物复合体的延伸构象中。在分子模拟的支持下，结构和生化数据使我们能够提出PolySia被EndNf切割的反应机理。
An α-2,8-linked polysialic acid (polySia) capsule confers immune tolerance to neuroinvasive, pathogenic prokaryotes such as Escherichia coli K1 and Neisseria meningitidis and supports host infection by means of molecular mimicry. Bacteriophages of the K1 family, infecting E. coli K1, specifically recognize and degrade this polySia capsule utilizing tailspike endosialidases. While the crystal structure for the catalytic domain of the endosialidase of bacteriophage K1F (endoNF) has been solved, there is yet no structural information on the mode of polySia binding and cleavage available. The crystal structure of activity deficient active-site mutants of the homotrimeric endoNF cocrystallized with oligomeric sialic acid identified three independent polySia binding sites in each endoNF monomer. The bound oligomeric sialic acid displays distinct conformations at each site. In the active site, a Sia3molecule is bound in an extended conformation representing the enzyme–product complex. Structural and biochemical data supported by molecular modeling enable to propose a reaction mechanism for polySia cleavage by endoNF.