Matsumoto K, Nagata K, Ui M, Hanaoka F
Cellular Physiology Laboratory, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
J Biol Chem. 1993 May 15;268(14):10582-7.
The adenovirus (Ad) genome in virion exists in the form of the Ad core, which is a complex of Ad DNA and viral basic proteins. The Ad core supported only initiation and limited elongation in DNA replication in a cell-free system which was developed for DNA replication of naked Ad DNA. We found that addition of a cytoplasmic fraction from uninfected HeLa cells on the top of the system stimulated Ad core DNA replication, although it had no effect on DNA replication of naked Ad DNA. The factor stimulating Ad core DNA replication, designated as template activating factor I (TAF-I), was purified by successive steps of ammonium sulfate precipitation, column chromatographies on phosphocellulose and Q-Sepharose, and glycerol density gradient centrifugation. SDS-polyacrylamide gel electrophoresis of the purified fraction revealed the presence of proteins with molecular masses of 41 and 39 kDa. TAF-I stimulated both initiation and elongation in Ad core DNA replication. Judging from its behavior in purification steps, TAF-I could be acidic. These findings suggest that TAF-I stimulates Ad core DNA replication by interaction with viral basic core proteins.
病毒粒子中的腺病毒（Ad）基因组以Ad核心的形式存在，Ad核心是Ad DNA与病毒碱性蛋白的复合物。在为裸露的Ad DNA复制而开发的无细胞系统中，Ad核心仅支持DNA复制的起始和有限的延伸。我们发现，在该系统顶部添加未感染的HeLa细胞的细胞质部分可刺激Ad核心DNA复制，尽管它对裸露的Ad DNA复制没有影响。刺激Ad核心DNA复制的因子被命名为模板激活因子I（TAF-I），通过硫酸铵沉淀、磷酸纤维素柱色谱和Q-琼脂糖柱色谱以及甘油密度梯度离心等连续步骤进行纯化。纯化部分的SDS-聚丙烯酰胺凝胶电泳显示存在分子量为41 kDa和39 kDa的蛋白质。TAF-I刺激Ad核心DNA复制的起始和延伸。从其在纯化步骤中的行为判断，TAF-I可能是酸性的。这些发现表明，TAF-I通过与病毒碱性核心蛋白相互作用来刺激Ad核心DNA复制。
