Takiya Shigeharu, Nishita Yoshinori, Ishikawa Susumu, Ohno Kaoru, Tamura Taka-aki, Suzuki Yoshiaki
Laboratory of Gene Function and Regulation, CAST, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan.
J Biochem. 2004 Jun;135(6):683-93. doi: 10.1093/jb/mvh082.
A new member of the Y-box protein family of the silkworm Bombyx mori (BYB) was co-purified with the fibroin gene enhancer-binding protein FMBP-1, and stimulated the binding of FMBP-1 to its cognate DNA element. However, the stimulatory effect was not specific to FMBP-1, BYB also enhancing the binding of mammalian transcription factors OTF2, SP1 and AP2 to their specific binding elements. Besides the above transcription regulatory factors, BYB facilitated the binding of basal transcription factor TBP, and enhanced transcription from the adenovirus 2 major late promoter in a reconstituted transcription system. Moreover, BYB stimulated the reactions of some restriction endonucleases under cold conditions. The C-terminal region of BYB was sufficient for these stimulatory effects, and the highly conserved cold shock domain (CSD) in the N-terminal region was dispensable. GST-pull down experiments showed that the C-terminal region could interact with DNA independently of the CSD. The above results suggest that the C-terminal region of BYB causes the active interaction of various DNA binding proteins with their targets. Such a function of the C-terminal region of BYB may partly explain the functional diversity of Y-box proteins.
家蚕Y盒蛋白家族的一个新成员（BYB）与丝素蛋白基因增强子结合蛋白FMBP-1共同纯化，并刺激FMBP-1与其同源DNA元件的结合。然而，这种刺激作用并非FMBP-1所特有，BYB还增强了哺乳动物转录因子OTF2、SP1和AP2与其特异性结合元件的结合。除上述转录调节因子外，BYB促进了基础转录因子TBP的结合，并在重组转录系统中增强了腺病毒2主要晚期启动子的转录。此外，BYB在低温条件下刺激了一些限制性内切酶的反应。BYB的C末端区域足以产生这些刺激作用，而N末端区域中高度保守的冷休克结构域（CSD）则是不必要的。GST下拉实验表明，C末端区域可独立于CSD与DNA相互作用。上述结果表明，BYB的C末端区域导致各种DNA结合蛋白与其靶标发生活性相互作用。BYB C末端区域的这种功能可能部分解释了Y盒蛋白的功能多样性。
