Replication of herpesvirus DNA. V. Maturation of concatemeric DNA of pseudorabies virus to genome length is related to capsid formation
Replication of herpesvirus DNA. V. Maturation of concatemeric DNA of pseudorabies virus to genome length is related to capsid formation
复制标题
疱疹病毒 DNA 的复制。
DOI：
10.1128/jvi.33.3.1151-1164.1980
复制
发表时间：
1980
影响因子：
5.4
通讯作者：
T. Ben‐Porat
中科院分区：
文献类型：
--
作者：
B. Ladin;M. Blankenship;T. Ben‐Porat
利用9个DNA+温度敏感的伪狂犬病毒突变体（每个突变体属于不同的互补群），研究了伪狂犬病毒DNA从复制型拼接体到基因组长度分子的成熟过程。在不允许的温度下，被每一种突变体感染的细胞合成了同源DNA。在所有DNA+ ts突变体中，拼接DNA与基因组长度的病毒DNA的切割都存在缺陷，这表明有几种病毒基因产物参与了DNA成熟过程。在所有被ts突变感染的细胞中都没有形成带有电子致密核（含有DNA）的衣壳。然而，在感染了9种温度敏感突变体中的6种的细胞中，形成了具有电子半透明核的空衣壳；在被三种突变体感染的细胞中，没有发生衣壳组装。由于这三种突变体都缺乏DNA的成熟和病毒衣壳的组装，我们得出结论，病毒DNA的成熟依赖于衣壳的组装。在感染了其中两种突变体（tsN和tsIE13）的细胞中，在环己亚胺存在下，细胞下移至允许温度后，病毒DNA发生了正常的成熟，这表明下移后参与DNA成熟的温度敏感蛋白开始发挥功能。此外，由于环己亚胺减少了野生型感染细胞中DNA的成熟，但在这两种突变体感染的细胞中没有，因此我们得出结论，在正常感染过程中，有一种蛋白质(s)在非允许温度下在突变体感染的细胞中积累，这种蛋白质在正常感染过程中数量有限。当tsn感染的细胞下降到允许的温度时，伴随着序列DNA的分裂，出现了具有电子致密核的完整衣壳，这表明DNA的成熟与完整衣壳的形成可能存在相关性。在非允许温度下培养的tsn感染细胞中，以及在环己亚胺存在下降至允许温度后，通过电子显微镜和蔗糖梯度中的沉降分析来确定空衣壳和满衣壳（含电子致密核）的数量。在环己亚胺存在下降至允许温度后，tsn感染细胞中的空衣壳数量减少，并伴随满衣壳的积累，这表明空衣壳是满衣壳的前体。
The maturation of pseudorabies virus DNA from the replicative concatemeric form to molecules of genome length was examined using nine DNA+ temperature-sensitive mutants of pseudorabies virus, each belonging to a different complementation group. At the nonpermissive temperature, cells infected with each of the mutants synthesized concatemeric DNA. Cleavage of the concatemeric DNA to genome-length viral DNA was defective in all the DNA+ ts mutants tested, indicating that several viral gene products are involved in the DNA maturation process. In none of the ts mutant-infected cells were capsids with electron-dense cores (containing DNA) formed. Empty capsids with electron-translucent cores were, however, formed in cells infected with six of the nine temperature-sensitive mutants; in cells infected with three of the mutants, no capsid assembly occurred. Because these three mutants are deficient both in maturation of DNA and in the assembly of viral capsids, we conclude that maturation of viral DNA is dependent upon the assembly of capsids. In cells infected with two of the mutants (tsN and tsIE13), normal maturation of viral DNA occurred after shiftdown of the cells to the permissive temperature in the presence of cycloheximide, indicating that the temperature-sensitive proteins involved in DNA maturation became functional after shiftdown. Furthermore, because cycloheximide reduces maturation of DNA in wild-type-infected cells but not in cells infected with these two mutants, we conclude that a protein(s) necessary for the maturation of concatemeric DNA, which is present in limiting amounts during the normal course of infection, accumulated in the mutant-infected cells at the nonpermissive temperature. Concomitant with cleavage of concatemeric DNA, full capsids with electron-dense cores appeared after shiftdown of tsN-infected cells to the permissive temperature, indicating that there may be a correlation between maturation of DNA and formation of full capsids. The number of empty and full capsids (containing electron-dense cores) present in tsN-infected cells incubated at the nonpermissive temperature, as well as after shiftdown to the permissive temperature in the presence of cycloheximide, was determined by electron microscopy and by sedimentation analysis in sucrose gradients. After shiftdown to the permissive temperature in the presence of cycloheximide, the number of empty capsids present in tsN-infected cells decreased with a concomitant accumulation of full capsids, indicating that empty capsids are precursors to full capsids.