Hoch M, Seifert E, Jäckle H
Max-Planck-Institut für biophysikalische Chemie, Abteilung Molekulare Entwicklungsbiologie, Göttingen, FRG.
EMBO J. 1991 Aug;10(8):2267-78. doi: 10.1002/j.1460-2075.1991.tb07763.x.
The initial expression of the gap gene Krüppel (Kr) occurs in a precisely bounded central region of the Drosophila blastoderm embryo. According to genetic analysis, the spatial limits of the Kr expression domain are controlled by the morphogenetic activities of the anterior organizer gene bicoid (bcd) and the anterior gap gene hunchback (hb). Using gene fusion analysis, we assayed for cis-acting sequences of the Kr gene which mediate transcriptional activation and localized gene expression in response to trans-acting factors. A 730 bp Kr control element drives gene expression in place of the endogenous Kr central domain. This cis-acting element, Kr730, is composed of bcd and hb responsive sequences. They map into regions of multiple hb and bcd protein in vitro binding sites. A 142 bp core fragment containing one low affinity hb and five medium to strong bcd protein binding sites drives gene expression in a Kr-like location in the centre of the embryo. Our results show that this fragment represents a target for the redundant activator/repressor system provided by the anterior morphogens bcd and hb.
间隙基因Krüppel（Kr）的初始表达出现在果蝇囊胚胚胎精确界定的中央区域。根据遗传分析，Kr表达域的空间界限受前部组织者基因双胸（bcd）和前部间隙基因驼背（hb）的形态发生活动控制。利用基因融合分析，我们检测了Kr基因的顺式作用序列，这些序列介导转录激活并响应反式作用因子进行基因定位表达。一个730 bp的Kr控制元件可替代内源性Kr中央结构域驱动基因表达。这个顺式作用元件Kr730由bcd和hb反应序列组成。它们定位于多个hb和bcd蛋白体外结合位点的区域。一个包含一个低亲和力hb和五个中到强bcd蛋白结合位点的142 bp核心片段在胚胎中央类似Kr的位置驱动基因表达。我们的结果表明，该片段代表了由前部形态发生素bcd和hb提供的冗余激活/抑制系统的一个靶点。
