Gottlieb P, Strassman J, Bamford D H, Mindich L
Department of Microbiology, Public Health Research Institute of the City of New York, Inc., New York 10016.
J Virol. 1988 Jan;62(1):181-7. doi: 10.1128/JVI.62.1.181-187.1988.
A polyhedral particle that resembles in composition and structure the procapsid of bacteriophage phi 6 was produced in Escherichia coli containing cDNA copies of the entire large genomic segment inserted into expression vector plasmids under the control of lac or tac promoters. The particles were composed of proteins P1, P2, P4, and P7 in the same stoichiometry as in the intact virion. In electron micrographs of negatively stained samples, the particles appeared as hexagons, stars, or rings of 10 knobs, which are characteristic of the five-, three-, and twofold axes of symmetry characteristic of phi 6 procapsids. Stable particles were also produced from cDNA deletions that produce only P1 and P4. Other cDNA deletions producing P1 and P7 and P1 alone resulted in unstable particles which could only be visualized in electron micrographs of thin sections of E. coli transformed by the recombinant plasmids. Our results indicate that the assembly of the phi procapsid is independent of other phage proteins and of normal phage RNA.
在含有插入到受乳糖或 tac 启动子控制的表达载体质粒中的完整大基因组片段 cDNA 拷贝的大肠杆菌中，产生了一种在组成和结构上类似于噬菌体 phi 6 原衣壳的多面体颗粒。这些颗粒由蛋白质 P1、P2、P4 和 P7 组成，其化学计量与完整病毒体中的相同。在负染色样品的电子显微照片中，颗粒呈现为六边形、星形或由 10 个瘤组成的环，这是 phi 6 原衣壳的五重、三重和二重对称轴的特征。仅产生 P1 和 P4 的 cDNA 缺失也产生了稳定颗粒。产生 P1 和 P7 以及仅产生 P1 的其他 cDNA 缺失导致不稳定颗粒，这些颗粒只能在由重组质粒转化的大肠杆菌薄切片的电子显微照片中观察到。我们的结果表明，phi 原衣壳的组装独立于其他噬菌体蛋白和正常噬菌体 RNA。
