Ambrose C, Blasquez V, Bina M
Proc Natl Acad Sci U S A. 1986 May;83(10):3287-91. doi: 10.1073/pnas.83.10.3287.
The initiation of simian virus 40 assembly is blocked at the nonpermissive temperature in cells infected with the viral capsid protein VP1 mutant tsC219. Greater than 95% of the minichromosomes isolated from these cells are accessible to cleavage by Bgl I and Sph I, which recognize the sequences near the viral replication origin and in the transcription enhancer elements, respectively. The accessibility of the Ori region to Bgl I is considerably reduced when virion assembly is allowed to proceed in tsC219-infected cells at the permissive temperature. A reduced accessibility to Bgl I is also observed for chromatin isolated from cells infected with wt776, the wild-type parental strain of tsC219. For wt776 chromatin, variability to Bgl I sensitivity is observed and this can be correlated to the relative virion-to-chromatin yield. A similar correlation is not apparent for restriction endonucleases that recognize sequences within the coding region of simian virus 40 chromatin. These results, considered together, indicate that, when virion assembly initiation is blocked, nucleosomes are nonrandomly arranged with respect to the viral regulatory sequences. It appears that the open regulatory region in minichromosomes is established during replication and that a protected regulatory region is generated with the onset of virion assembly.
在感染病毒衣壳蛋白VP1突变体tsC219的细胞中，猴病毒40装配的起始在非允许温度下被阻断。从这些细胞中分离出的大于95%的微型染色体可被Bgl I和Sph I切割，Bgl I和Sph I分别识别病毒复制起点附近和转录增强子元件中的序列。当在允许温度下，tsC219感染的细胞中进行病毒体装配时，Ori区域对Bgl I的可及性显著降低。从感染了tsC219的野生型亲本菌株wt776的细胞中分离的染色质，对Bgl I的可及性也降低。对于wt776染色质，观察到对Bgl I敏感性的变异性，这可能与病毒体与染色质产量的相对关系有关。对于识别猴病毒40染色质编码区域内序列的限制性内切酶，类似的相关性并不明显。综合这些结果表明，当病毒体装配起始被阻断时，核小体相对于病毒调控序列呈非随机排列。似乎微型染色体中的开放调控区域在复制过程中建立，并且随着病毒体装配的开始产生一个受保护的调控区域。
