Yuan D, Ma X, Ma J
Division of Developmental Biology, Children's Hospital Research Foundation, and Graduate Program in Developmental Biology, University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, Ohio, 45229-3039, USA.
J Biochem. 1999 Apr;125(4):809-17. doi: 10.1093/oxfordjournals.jbchem.a022353.
Our previous studies demonstrated that the Drosophila homeodomain protein, Bicoid (Bcd), binds DNA cooperatively. In this study, we determined the patterns of adjacent DNA sites required for cooperative recognition by Bcd. Our in vitro selection and biochemical experiments demonstrated that Bcd binds preferentially to both head-to-head and tail-to-tail symmetric sites that are separated by short spacing. An increase in the spacing reduces the strict requirement of symmetric patterns of adjacent sites, permitting Bcd to recognize tandem repeat sites cooperatively. Our further experiments in vivo showed that the only pair of optimally spaced symmetric Bcd sites in a hunchback (hb) enhancer element contributes the most to transcriptional activation by Bcd, demonstrating the biological importance of the binding site patterns revealed by our in vitro selection studies.
我们之前的研究表明，果蝇同源结构域蛋白双胸蛋白（Bicoid，Bcd）能协同结合DNA。在本研究中，我们确定了Bcd协同识别所需的相邻DNA位点模式。我们的体外筛选和生化实验表明，Bcd优先结合由短间距隔开的头对头和尾对尾对称位点。间距增加会降低对相邻位点对称模式的严格要求，使Bcd能够协同识别串联重复位点。我们在体内的进一步实验表明，驼背（hunchback，hb）增强子元件中唯一一对间距最佳的对称Bcd位点对Bcd的转录激活贡献最大，这证明了我们体外筛选研究所揭示的结合位点模式的生物学重要性。
