Nagata K, Kawase H, Handa H, Yano K, Yamasaki M, Ishimi Y, Okuda A, Kikuchi A, Matsumoto K
Department of Biomolecular Engineering, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan.
Proc Natl Acad Sci U S A. 1995 May 9;92(10):4279-83. doi: 10.1073/pnas.92.10.4279.
DNA replication of the adenovirus genome complexed with viral core proteins is dependent on the host factor designated template activating factor I (TAF-I) in addition to factors required for replication of the naked genome. Recently, we have purified TAF-I as 39- and 41-kDa polypeptides from HeLa cells. Here we describe the cloning of two human cDNAs encoding TAF-I. Nucleotide sequence analysis revealed that the 39-kDa polypeptide corresponds to the protein encoded by the set gene, which is the part of the putative oncogene associated with acute undifferentiated leukemia when translocated to the can gene. The 41-kDa protein contains the same amino acid sequence as the 39-kDa protein except that short N-terminal regions differ in both proteins. Recombinant proteins, which were purified from extracts of Escherichia coli, expressing the proteins from cloned cDNAs, possessed TAF-I activities in the in vitro replication assay. A particular feature of TAF-I proteins is the presence of a long acidic tail in the C-terminal region, which is thought to be an essential part of the SET-CAN fusion protein. Studies with mutant TAF-I proteins devoid of this acidic region indicated that the acidic region is essential for TAF-I activity.
与病毒核心蛋白复合的腺病毒基因组的DNA复制，除了裸基因组复制所需的因子外，还依赖于一种名为模板激活因子I（TAF-I）的宿主因子。最近，我们从HeLa细胞中纯化出了39 kDa和41 kDa的TAF-I多肽。在此，我们描述了编码TAF-I的两个人类cDNA的克隆。核苷酸序列分析表明，39 kDa的多肽对应于set基因编码的蛋白质，当该基因易位到can基因时，它是与急性未分化白血病相关的假定癌基因的一部分。41 kDa的蛋白质与39 kDa的蛋白质具有相同的氨基酸序列，只是两种蛋白质的N端短区域有所不同。从表达克隆cDNA编码蛋白的大肠杆菌提取物中纯化得到的重组蛋白，在体外复制试验中具有TAF-I活性。TAF-I蛋白的一个特殊特征是在C端区域存在一条长的酸性尾巴，这被认为是SET-CAN融合蛋白的一个重要部分。对缺失该酸性区域的突变TAF-I蛋白的研究表明，酸性区域对TAF-I活性至关重要。
