CHARACTERIZATION OF AUTOREGULATION OF SIMIAN VIRUS-40 GENE-A
CHARACTERIZATION OF AUTOREGULATION OF SIMIAN VIRUS-40 GENE-A
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DOI：
10.1128/jvi.24.1.22-27.1977
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发表时间：
1977-01-01
影响因子：
5.4
通讯作者：
STARK, GR
中科院分区：
文献类型：
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作者：
ALWINE, JC;REED, SI;STARK, GR
被SV40的TSA突变体感染的细胞[非洲绿猴肾CV-1]过度产生早期RNA。过量生产的原因是温度敏感型A蛋白(T[肿瘤]抗原)未能抑制早期转录。通过与标记的互补SV40 DNA杂交的动力学测定，细胞质中早期RNA的数量在允许的范围内(32度)增加。C)和不允许(41度。C)所有早期突变体(tsA7、-30、-58和-209)中的温度，但晚期突变体tsB4中没有。培养物中早期核糖核糖核酸的量保持在32度。C反应72h，然后移至41℃。当每个细胞最初被至少1个空斑形成单位tsA58感染时，c最大。抑制DNA合成的叠氮胞苷(2‘’-脱氧-2‘’-叠氮胞苷)不能引起野生型SV40感染细胞早期RNA的过量生产，这表明TSA突变体的作用不是由于干扰DNA合成本身。在41度平行感染中。C，即使没有复制tsA58 DNA，tsA58病毒DNA的每个拷贝的早期RNA量也是野生型SV40的2000倍。在任一病毒32度感染的前20小时内，都不能检测到晚期RNA的合成。C，表明晚期转录和早期转录受到不同的控制。在TSA突变体转化的3株细胞中，早期RNA的量在32-41度转变后略有增加。C，但用野生型病毒转化的同源细胞，早期RNA的数量减少，表明A蛋白可能能够抑制整合的SV40DNA的转录。所有这些观察结果都符合一个简单的模型，即复制起始处A蛋白的结合阻止了RNA聚合酶与早期启动子的结合或通过早期基因的进展(S)。
Cells [African green monkey kidney CV-1] infected by tsA mutants of SV40 overproduce early RNA. Overproduction results from failure of the temperature-sensitive A protein (T [tumor] antigen) to inhibit early transcription. The amount of early RNA in the cytoplasm, determined quantitatively from the kinetics of hybridization to labeled complementary SV40 DNA, was elevated at permissive (32.degree. C) and nonpermissive (41.degree. C) temperatures in all the early mutants tested (tsA7, -30, -58 and -209), but not in the late mutant tsB4. The amount of early RNA in a culture maintained at 32.degree. C for 72 h and then shifted to 41.degree. C was maximum when each cell was infected initially with at least 1 plaque-forming unit of tsA58. Azidocytidine (2''-deoxy-2''-azidocytidine), which inhibits initiation of DNA synthesis, did not cause overproduction of early RNA in cells infected with wild-type SV40, showing that the effect seen with tsA mutants is not due to interference with initiation of DNA synthesis per se. In parallel infections at 41.degree. C, the amount of early RNA per copy of viral DNA was as much as 2000 times greater with tsA58 than with wild-type SV40, even though there was no replication of the tsA58 DNA. Synthesis of late RNA could not be detected during the first 20 h of an infection by either virus at 32.degree. C, indicating that late and early transcription are under different control. In 3 cell lines transformed by tsA mutants, the amount of early RNA increased moderately after a shift from 32-41.degree. C, but with homologous cells transformed by wild-type virus, the amount of early RNA decreased, indicating that the A protein may be able to repress transcription of integrated SV40 DNA. All the observations are consistent with a simple model in which the binding of A protein at the origin of replication blocks binding of RNA polymerase to the early promoter or its progress through the early gene(s).