Kagoshima H, Akamatsu Y, Ito Y, Shigesada K
Laboratory of Biochemistry, Department of Genetics and Molecular Biology, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606, Japan.
J Biol Chem. 1996 Dec 20;271(51):33074-82. doi: 10.1074/jbc.271.51.33074.
The mouse transcription factor PEBP2 is a heterodimer of two subunits: a DNA binding subunit alpha and its partner subunit beta. The alpha subunit shares a region of high homology, termed the Runt domain, with the products of the Drosophila melanogaster segmentation gene runt and the human acute myeloid leukemia-related gene AML1. To study the molecular basis for the DNA binding and heterodimerization functions of this factor, we constructed series of deletions of the alpha and beta subunits and examined their activities by electrophoretic mobility shift and affinity column assays. The minimal functional region of the alpha subunit for DNA binding and dimerization was shown to coincide with the Runt domain. On the other hand, the region of the beta subunit required for heterodimerization was localized to the N-terminal 135 amino acids. Furthermore, it was found that the DNA binding activity of the Runt domain is regulated by a reduction/oxidization (redox) mechanism and that its reductively activated state, which is extremely labile, is stabilized by the beta subunit. These findings add a new layer to the mechanism and significance of the regulatory interplay between the two subunits of PEBP2.
小鼠转录因子PEBP2是由两个亚基组成的异二聚体：一个DNA结合亚基α及其伙伴亚基β。α亚基与果蝇体节基因runt的产物以及人类急性髓系白血病相关基因AML1的产物共享一个高度同源的区域，称为Runt结构域。为了研究该因子DNA结合和异二聚化功能的分子基础，我们构建了α和β亚基的一系列缺失体，并通过电泳迁移率变动分析和亲和柱分析检测了它们的活性。结果表明，α亚基用于DNA结合和二聚化的最小功能区域与Runt结构域一致。另一方面，异二聚化所需的β亚基区域定位于N端的135个氨基酸。此外，还发现Runt结构域的DNA结合活性受还原/氧化（氧化还原）机制调节，其还原激活状态极其不稳定，但能被β亚基稳定。这些发现为PEBP2两个亚基之间调节相互作用的机制和意义增添了新的内容。
