Gyurcsik Béla, Haruki Hirohito, Takahashi Tsuyoshi, Mihara Hisakazu, Nagata Kyosuke
Department of Infection Biology, Graduate School of Comprehensive Human Sciences, and Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan.
Biochemistry. 2006 Jan 10;45(1):303-13. doi: 10.1021/bi051248+.
Template Activating Factor (TAF) I remodels the adenovirus (Ad) core structure composed of the Ad genome DNA and basic viral core proteins and stimulates in vitro DNA replication and transcription of the Ad core. We have recently reported that TAF-I binds to major core protein VII and forms DNA-protein VII-TAF-I ternary complexes in vitro and in vivo. Further to understand the mechanism of remodeling of the Ad core, we characterized the interaction mode between the precursor of protein VII (pre-VII) and either DNA or TAF-I by means of biochemical and biophysicochemical methods. We found that a major binding region of pre-VII with both DNA and the acidic carboxyl-terminal region of TAF-I lies in the arginine-rich region of pre-VII. Both amino-terminal and carboxyl-terminal regions of pre-VII without the arginine-rich region directly bound to DNA and supported the DNA binding activity of the arginine-rich region. A TAF-I mutant protein lacking the acidic carboxyl-terminal region bound preferentially to the carboxyl-terminal region of pre-VII containing the arginine-rich region rather than the amino-terminal region of pre-VII. Thus, DNA interacted with the entire region of pre-VII, while TAF-I bound preferentially to the carboxyl-terminal region of pre-VII. This binding mode suggests the formation of the ternary complexes among DNA, protein VII, and TAF-I. On the basis of the binding modes in binary systems, we discussed the remodeling mechanism of the Ad core in early phases of infection.
模板激活因子（TAF）I重塑由腺病毒（Ad）基因组DNA和基本病毒核心蛋白组成的腺病毒核心结构，并在体外刺激腺病毒核心的DNA复制和转录。我们最近报道，TAF-I在体外和体内均与主要核心蛋白VII结合并形成DNA-蛋白VII-TAF-I三元复合物。为了进一步了解腺病毒核心重塑的机制，我们通过生化和生物物理化学方法对蛋白VII前体（pre-VII）与DNA或TAF-I之间的相互作用模式进行了表征。我们发现，pre-VII与DNA和TAF-I酸性羧基末端区域的主要结合区域位于pre-VII的富含精氨酸区域。pre-VII不含富含精氨酸区域的氨基末端和羧基末端区域直接与DNA结合，并支持富含精氨酸区域的DNA结合活性。缺乏酸性羧基末端区域的TAF-I突变蛋白优先与包含富含精氨酸区域的pre-VII羧基末端区域结合，而不是与pre-VII的氨基末端区域结合。因此，DNA与pre-VII的整个区域相互作用，而TAF-I优先与pre-VII的羧基末端区域结合。这种结合模式表明在DNA、蛋白VII和TAF-I之间形成了三元复合物。基于二元系统中的结合模式，我们讨论了感染早期腺病毒核心的重塑机制。
