卫星噬菌体P4 DNA的体外包装
In vitro packaging of satellite phage P4 DNA.
作者信息
Pruss G, Goldstein R N, Calendar R
出版信息
Proc Natl Acad Sci U S A. 1974 Jun;71(6):2367-71. doi: 10.1073/pnas.71.6.2367.
Satellite phage P4 directs the capsid proteins of its helper phage, P2, to form a head which is only one-third the size of the normal P2 head. The P2 head contains a genome of molecular weight 22 x 10(6), while the small P4 head contains a genome with a molecular weight of only 7 x 10(6). We have used in vitro DNA packaging to test whether P2 and P4 phage head sizes are determined by DNA size. The small DNA of satellite phage P4 added to a P2-infected cell extract was packaged primarily into particles containing three copies of the P4 genome. This process occurred with approximately the same efficiency as P2 DNA packaging in the same cell extract. In contrast, the large DNA of P2 was packaged 300-fold less efficiently than the small DNA of P4 in an extract derived from P4-infected, P2-lysogenic cells. These results suggest that DNA size is not sufficient to determine head size. The results are compatible with DNA packaging via the filling of preformed empty capsids.
卫星噬菌体P4指导其辅助噬菌体P2的衣壳蛋白形成一种头部，其大小仅为正常P2头部的三分之一。P2头部含有分子量为22×10⁶的基因组，而小的P4头部含有分子量仅为7×10⁶的基因组。我们利用体外DNA包装来测试P2和P4噬菌体头部大小是否由DNA大小决定。添加到P2感染细胞提取物中的卫星噬菌体P4的小DNA主要被包装到含有三个P4基因组拷贝的颗粒中。这个过程与在相同细胞提取物中包装P2 DNA的效率大致相同。相比之下，在源自P4感染、P2溶原性细胞的提取物中，P2的大DNA包装效率比P4的小DNA低300倍。这些结果表明，DNA大小不足以决定头部大小。这些结果与通过填充预先形成的空衣壳进行DNA包装是相符的。
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