Tenen D G, Martin R G, Anderson J, Livingston D M
J Virol. 1977 Apr;22(1):210-8. doi: 10.1128/JVI.22.1.210-218.1977.
The growth properties of hamster cells transformed by wild-type Simian virus 40 (SV40), by early SV40 temperature-sensitive mutants of the A complementation group, and by spontaneous revertants of these mutants were studied. All of the tsA mutant-transformed cells were temperature sensitive in their ability to form clones in soft agar and on monolayers of normal cells except for CHLA-30L1, which was not temperature sensitive in the latter property. All cells transformed by stable revertants of well-characterized tsA mutants possessed certain growth properties in common with wild-type-transformed cells at both temperatures. Virus rescued from tsA transformants including CHLA30L1 was temperature sensitive for viral DNA replication, whereas that rescued from revertant and wild-type transformants was not thermolabile in this regard. T antigen present in crude extracts of tsA-transformed cells including CHLA30L1, grown at 33 degreeC, was temperature sensitive by in vitro immunoassay, whereas that from wild-type-transformed cells was relatively stable. T antigen from revertant transformants was more stable than the tsA protein. Partially purified T antigen from revertant-transformed cells was nearly as stable as wild-type antigen in its ability to bind DNA after heating at 44 degrees C, whereas T antigen from tsA30 mutant-transformed cells was relatively thermolabile. These results further indicate that T antigen is a product of the SV40 A gene. Significantly more T antigen was found in extracts of CHLA30L1 grown to high density at the nonpermissive temperature than in any other tsA-transformed cell similarly grown. This is consistent with the suggestion that the amount of T antigen synthesized in CHLA30L1 is large enoughto allow partial expression of the transformed phenotype at the restrictive temperature. Alternatively, the increase in T antigen concentration may be secondary to one or more genetic alterations that independently affect the transformed phenotype of these cells.
研究了野生型猴病毒40(SV40)、A互补组的早期SV40温度敏感突变体以及这些突变体的自发回复体转化的仓鼠细胞的生长特性。除了CHLA - 30L1在正常细胞单层上形成克隆的能力不具有温度敏感性外,所有tsA突变体转化的细胞在软琼脂中及在正常细胞单层上形成克隆的能力均具有温度敏感性。由特征明确的tsA突变体的稳定回复体转化的所有细胞在两个温度下都具有与野生型转化细胞共同的某些生长特性。从包括CHLA30L1在内的tsA转化体中拯救的病毒在病毒DNA复制方面具有温度敏感性,而从回复体和野生型转化体中拯救的病毒在这方面不具有热不稳定性。在33℃生长的包括CHLA30L1在内的tsA转化细胞的粗提物中存在的T抗原,通过体外免疫测定具有温度敏感性,而来自野生型转化细胞的T抗原相对稳定。来自回复体转化体的T抗原比tsA蛋白更稳定。在44℃加热后,从回复体转化细胞中部分纯化的T抗原结合DNA的能力几乎与野生型抗原一样稳定,而来自tsA30突变体转化细胞的T抗原相对热不稳定。这些结果进一步表明T抗原是SV40 A基因的产物。在非允许温度下生长至高密度的CHLA30L1提取物中发现的T抗原明显多于同样生长的任何其他tsA转化细胞。这与以下观点一致,即CHLA30L1中合成的T抗原量足够大,能够在限制温度下部分表达转化表型。或者,T抗原浓度的增加可能是一个或多个独立影响这些细胞转化表型的基因改变的结果。