Epitope mapping of histo blood group antigens bound to norovirus VLPs using STD NMR experiments reveals fine details of molecular recognition
Epitope mapping of histo blood group antigens bound to norovirus VLPs using STD NMR experiments reveals fine details of molecular recognition
复制标题
DOI：
10.1007/s10719-017-9792-5
复制
发表时间：
2017-10-01
影响因子：
3
通讯作者：
Peters, Thomas
中科院分区：
文献类型：
--
作者：
Fiege, Brigitte;Leuthold, Mila;Peters, Thomas
人诺如病毒与组织血型抗原（HBGAs）的结合被认为是感染过程的关键。因此，我们使用STD NMR实验确定了与GII. 4人诺如病毒病毒样颗粒（VLP）结合的合成1型至6型血型A-和B-四糖的结合表位。到目前为止，从晶体结构分析研究的还原性末端糖与病毒外壳蛋白VP 1的突出结构域（P-结构域）的相互作用的信息很少。在这里，我们表明，还原端糖与蛋白质表面显着的接触。糖苷键的类型和还原端糖的特性调节HBGA识别。最引人注目的是，2型结构仅产生非常差的饱和转移，表明结合受阻。该观察结果与先前基于质谱法的亲和力测量一致，并且可以基于高度同源的GII. 4 P-二聚体与H-2型三糖的复合物的最近晶体结构数据来理解，其中还原性N-乙酰基葡糖胺残基的N-乙酰基指向包含氨基酸Q390至H395的环。我们认为，在我们的情况下，2型A-和B-四糖的结合导致与此循环的空间冲突。为了鉴定决定L-Fuc识别的因素，我们还合成了具有点突变D391 A和H395 A的GII.4 VLP。以前的研究表明，这些残基，位于第二个壳周围的L-Fuc结合位点，协助L-Fuc的结合。在野生型和突变VLP存在下用L-Fuc和B-三糖进行的STD NMR实验产生几乎相同的结合表位，表明这两种突变不会显著改变HBGA识别。我们的研究强调，α-（1 -> 2）-连接的L-Fuc残基的识别是GII. 4诺如病毒的保守特征。然而，HBGA核心结构的结构变化明显地调节取决于基因型的分子识别。
Attachment of human noroviruses to histo blood group antigens (HBGAs) is thought to be critical for the infection process. Therefore, we have determined binding epitopes of synthetic type 1 to 6 blood group A- and B-tetrasaccharides binding to GII.4 human Norovirus virus like particles (VLPs) using STD NMR experiments. So far, little information is available from crystal structure analysis studies on the interactions of the reducing-end sugars with the protruding domain (P-domain) of the viral coat protein VP1. Here, we show that the reducing-end sugars make notable contacts with the protein surface. The type of glycosidic linkage, and the identity of the sugar at the reducing end modulate HBGA recognition. Most strikingly, type 2 structures yield only very poor saturation transfer indicating impeded binding. This observation is in accordance with previous mass spectrometry based affinity measurements, and can be understood based on recent crystal structure data of a complex of highly homologous GII.4 P-dimers with H-type 2 trisaccharide where the N-acetyl group of the reducing N-acetyl glucosamine residue points towards a loop comprising amino acids Q390 to H395. We suggest that in our case, binding of type 2 A- and B-tetrasaccharides leads to steric conflicts with this loop. In order to identify factors determining L-Fuc recognition, we also synthesized GII.4 VLPs with point mutations D391A and H395A. Prior studies had suggested that these residues, located in a second shell around the L-Fuc binding site, assist L-Fuc binding. STD NMR experiments with L-Fuc and B-trisaccharide in the presence of wild type and mutant VLPs yield virtually identical binding epitopes suggesting that these two mutations do not significantly alter HBGA recognition. Our study emphasizes that recognition of alpha-(1 -> 2)-linked L-Fuc residues is a conserved feature of GII.4 noroviruses. However, structural variation of the HBGA core structures clearly modulates molecular recognition depending on the genotype.