Isaksen M L, Rishovd S T, Calendar R, Lindqvist B H
Institute of Biology, University of Oslo, Norway.
Virology. 1992 Jun;188(2):831-9. doi: 10.1016/0042-6822(92)90538-z.
We show that the product of the polarity suppression (psu) gene from bacteriophage P4 associates with P4 capsids. This association can occur when Psu is (i) provided in vivo from the P4 genome or from a plasmid or (ii) provided in vitro by mixing viable phage particles with Psu protein. Psu is unable to associate with the larger capsid of P4's helper phage P2. Discrimination of the P4 and P2 capsids by Psu appears to be independent of the presence of the P4 genome in the capsid, since P2 size capsids filled with P4 DNA cannot accommodate Psu association. P4 psu particles devoid of Psu are less stable than P4 particles carrying Psu. These results indicate that, in addition to its antitermination activity at Rho-dependent terminators, Psu is also a decoration protein that stabilizes the P4 capsids.
我们发现，来自噬菌体P4的极性抑制（psu）基因产物与P4衣壳相关联。当Psu以以下方式存在时，这种关联就会发生：（i）在体内由P4基因组或质粒提供，或者（ii）在体外通过将活噬菌体颗粒与Psu蛋白混合提供。Psu无法与P4的辅助噬菌体P2的较大衣壳相关联。Psu对P4和P2衣壳的区分似乎与衣壳中P4基因组的存在无关，因为填充有P4 DNA的P2大小的衣壳无法容纳Psu的关联。不含Psu的P4 psu颗粒比携带Psu的P4颗粒稳定性更低。这些结果表明，除了其在依赖Rho的终止子处的抗终止活性外，Psu还是一种可稳定P4衣壳的装饰蛋白。
