Function and structure of the spike H protein of bacteriophage φX174 directing infection to host cell

细菌脂多糖的脂类部分在刺激性H蛋白识别中的作用用水合肼和氢氧化钾处理大肠杆菌C中的内毒素，得到脱酰化的内毒素衍生物。这些衍生物对噬菌体φX174的Spike II蛋白的亲和力显著降低，构象变化也很小。这些衍生物被提交给与Spike H和G蛋白相互作用的估计。H蛋白受磷酸盐残基丢失的影响，G蛋白受内毒素KDO残基丢失的影响识别。S蛋白抗蛋白酶结构域的分离与鉴定通过VS酶的温和处理，H蛋白产生了两个抗蛋白酶结构域(F2和F3)。N-末端氨基酸观察和MALDI-TOF-MS分析表明。F2对应215-345个残基片段，F3对应H蛋白1-102个残基片段。与完整的H蛋白相比，片段F2与宿主细菌的内毒素具有较强的亲和力，而片段F1与完整的H蛋白的亲和力为1/10。

Contribution of lipid part of LPS to the recognition by spike H proteinThe LPS of E. coli C was treated with hydradine and potassium hydroxide to gave the deacylated derivatives of LPS. The derivatives showed significantly less affinity and small magnitude of conformational change toward the spike II protein of bacteriophage φX174 Contribution of charged residues of LPS to the recognition by spike H and G proteinsThe derivatives of dephosphorylated and KDO reduced derivatives were prepared by the limited chemical degradation of LPS by hydrogen fluoride and sodium borohydride coupled with water soluble carbodiimide. These derivatives were submitted to the estimation of the interaction with the spike H and G proteins. The H protein was affected by the loss of phosphate residue and the G protein was affected by the loss of KDO residue from the LPS for the recognition.Isolation and characterization of the protease resistance domains of spike H proteinBy a mild treatment with VS protease, H protein gave two protease resistant domains(F2 and F3). The observations of N-terminal amino acid and MALDI-TOF-MS analyses revealed that. F2 corresponded to the fragment of 215-345 residues, on the other hand, F3 corresponded to the fragment of 1-102 residues of H protein. The fragment F2 showed strong affinity toward the LPS of host bacteria compared to the intact H protein, however, the fragment Fl showed 1/10 affinity to the intact H protein.