Terry T D, Malik P, Perham R N
Cambridge Centre for Molecular Recognition, Department of Biochemistry, University of Cambridge, UK.
Biol Chem. 1997 Jun;378(6):523-30. doi: 10.1515/bchm.1997.378.6.523.
The genome of the filamentous bacteriophage fd has been engineered so that small peptides can be inserted into the exposed N-terminal segment of pVIII, the major protein of the virus capsid. Most small peptides can be displayed on all 2700 copies of pVIII (a recombinant virion), but larger peptides can be displayed only in virions in which modified and wild-type proteins are intermingled (hybrid virions). Peptides displayed in this way are highly immunogenic and capable of interacting with receptors and other ligands. The physical accessibility of the displayed peptides was tested by examining their susceptibility to digestion with proteinases. Potential cleavage sites in peptides displayed on recombinant or hybrid virions were in general found to be accessible to trypsin and chymotrypsin; and the density of incorporation of peptides in the virion had no effect on the susceptibility to cleavage. However, peptide bonds towards the C-terminal end of an insert, located approximately 47 residues or fewer from the C-terminus of the coat protein, were protected from digestion, presumably because of their proximity to the bulk viral surface. These results have important implications for the design and optimization of peptide display systems using filamentous bacteriophages.
丝状噬菌体fd的基因组已被改造，以便将小肽插入病毒衣壳的主要蛋白pVIII暴露的N端片段中。大多数小肽可以展示在所有2700个pVIII拷贝上（重组病毒粒子），但较大的肽只能展示在修饰蛋白和野生型蛋白混合的病毒粒子中（杂交病毒粒子）。以这种方式展示的肽具有高度免疫原性，并且能够与受体和其他配体相互作用。通过检测展示肽对蛋白酶消化的敏感性来测试其物理可及性。一般发现，重组或杂交病毒粒子上展示的肽中的潜在切割位点对胰蛋白酶和胰凝乳蛋白酶是可及的；并且肽在病毒粒子中的掺入密度对切割敏感性没有影响。然而，插入片段C端附近的肽键，即距离衣壳蛋白C端约47个残基或更少的肽键，受到消化保护，推测是因为它们靠近病毒的主体表面。这些结果对使用丝状噬菌体的肽展示系统的设计和优化具有重要意义。
