Endemann H, Model P
Rockefeller University, New York, NY 10021, USA.
J Mol Biol. 1995 Jul 21;250(4):496-506. doi: 10.1006/jmbi.1995.0393.
We show that all minor coat proteins of phage f1 are integral inner membrane proteins prior to assembly. Hence all phage structural and morphogenetic proteins are localized in the membrane of the infected cell, consistent with models of phage assembly in which morphogenesis is coincident with phage extrusion. Our data suggest that the minor coat proteins, pVI and pIII, are already associated with the major coat protein, pVIII, in the membrane. On the other hand pVI and pIII are not recovered as a complex from the membrane, even though experiments with dissociated phage show they are associated in phage. The minor coat proteins, pVII and pVIII, are also associated in phage. With the use of sera directed against the minor proteins, we show that the minor coat protein, pIX, is accessible in intact phage, but pVI and pVII are not. Consistent with earlier results, the attachment protein, pIII, clearly is exposed on the phage exterior. Infected cells contain about ten times more pVII and pIX than is incorporated into phage.
我们发现，噬菌体f1的所有次要外壳蛋白在组装之前都是整合内膜蛋白。因此，所有噬菌体结构蛋白和形态发生蛋白都定位于被感染细胞的膜中，这与噬菌体组装模型一致，在该模型中形态发生与噬菌体挤出同时发生。我们的数据表明，次要外壳蛋白pVI和pIII在膜中已经与主要外壳蛋白pVIII相关联。另一方面，尽管解离噬菌体的实验表明pVI和pIII在噬菌体中相关联，但它们并未作为复合物从膜中回收。次要外壳蛋白pVII和pVIII在噬菌体中也相关联。通过使用针对次要蛋白的血清，我们发现次要外壳蛋白pIX在完整噬菌体中可及，但pVI和pVII不可及。与早期结果一致，附着蛋白pIII显然暴露于噬菌体外部。被感染细胞中pVII和pIX的含量比整合到噬菌体中的多约十倍。
