Wilson A C, Freiman R N, Goto H, Nishimoto T, Herr W
Cold Spring Harbor Laboratory, New York 11724, USA.
Mol Cell Biol. 1997 Oct;17(10):6139-46. doi: 10.1128/MCB.17.10.6139.
The herpes simplex virus (HSV) regulatory protein VP16 activates HSV immediate-early gene transcription through formation of a multiprotein-DNA complex on viral promoters that includes the preexisting nuclear proteins HCF and Oct-1. The HCF protein is a complex of amino- and carboxy-terminal polypeptides derived from a large (approximately 2,000-amino-acid) precursor by proteolytic processing. Here we show that a 361-residue amino-terminal region of HCF is sufficient to bind VP16, stabilize VP16-induced complex assembly with Oct-1 and DNA, and activate transcription in vivo. This VP16 interaction region contains six kelch-like repeats, a degenerate repeat motif that is likely to fold as a distinctive beta-propeller structure. The third HCF kelch repeat includes a proline residue (P134) that is mutated to serine in hamster tsBN67 cells, resulting in a temperature-sensitive defect in cell proliferation. This missense mutation also prevents direct association between HCF and VP16, suggesting that VP16 mimics a cellular factor required for cell proliferation. Rescue of the tsBN67 cell proliferation defect by HCF, however, requires both the VP16 interaction domain and an adjacent basic region, indicating that HCF utilizes multiple regions to promote cell cycle progression.
单纯疱疹病毒（HSV）调节蛋白VP16通过在病毒启动子上形成一种多蛋白-DNA复合物来激活HSV立即早期基因转录，该复合物包含预先存在的核蛋白HCF和Oct-1。HCF蛋白是一种氨基末端和羧基末端多肽的复合物，由一个大的（约2000个氨基酸）前体经蛋白水解加工而成。在这里，我们表明HCF的一个361个残基的氨基末端区域足以结合VP16，稳定VP16诱导的与Oct-1和DNA的复合物组装，并在体内激活转录。这个VP16相互作用区域包含六个kelch样重复序列，这是一个可能折叠成独特β-螺旋桨结构的简并重复基序。HCF的第三个kelch重复序列包含一个脯氨酸残基（P134），在仓鼠tsBN67细胞中该残基突变为丝氨酸，导致细胞增殖出现温度敏感缺陷。这个错义突变也阻止了HCF与VP16之间的直接结合，这表明VP16模拟了细胞增殖所需的一种细胞因子。然而，HCF对tsBN67细胞增殖缺陷的挽救需要VP16相互作用结构域和一个相邻的碱性区域，这表明HCF利用多个区域来促进细胞周期进程。
