Matsumoto K, Okuwaki M, Kawase H, Handa H, Hanaoka F, Nagata K
Cellular Physiology Laboratory, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
J Biol Chem. 1995 Apr 21;270(16):9645-50. doi: 10.1074/jbc.270.16.9645.
Adenovirus (Ad) genome DNA is complexed with viral core proteins in the virus particle and in host cells during the early stages of infection. This DNA protein complex, called Ad core, is thought to be the template for transcription and DNA replication in infected cells. The Ad core functioned as template for DNA replication in the cell-free system consisting of viral replication proteins, uninfected HeLa nuclear extracts, and a novel factor, template activating factor-I (TAF-I) that we have isolated from uninfected HeLa cytoplasmic fractions. The Ad core did not function as an efficient template in the cell-free transcription system with nuclear extracts of uninfected HeLa cells. The addition of TAF-I resulted in the stimulation of transcription from E1A and ML promoters on the Ad core. TAF-I was required, at least, for the formation of preinitiation complexes. These observations suggest that, in addition to factors essential for transcription on naked DNA template, the factor such as TAF-I needed for replication of the Ad core is also required for transcription from the Ad genome in a chromatin-like structure.
腺病毒（Ad）基因组DNA在病毒颗粒中以及在感染早期的宿主细胞中与病毒核心蛋白复合。这种被称为Ad核心的DNA-蛋白质复合物被认为是受感染细胞中转录和DNA复制的模板。在由病毒复制蛋白、未感染的HeLa细胞核提取物以及我们从未感染的HeLa细胞质组分中分离出的一种新因子——模板激活因子-I（TAF-I）组成的无细胞系统中，Ad核心充当DNA复制的模板。在使用未感染的HeLa细胞核提取物的无细胞转录系统中，Ad核心不能作为有效的模板。添加TAF-I导致Ad核心上E1A和ML启动子的转录受到刺激。至少，预起始复合物的形成需要TAF-I。这些观察结果表明，除了裸DNA模板转录所必需的因子外，Ad核心复制所需的诸如TAF-I之类的因子对于从染色质样结构的Ad基因组进行转录也是必需的。
