Chiang T Y, Marzluf G A
Department of Biochemistry, Ohio State University, Columbus 43210.
Biochemistry. 1994 Jan 18;33(2):576-82. doi: 10.1021/bi00168a024.
NIT2, a global positive-acting regulatory protein in Neurospora crassa, activates the expression of a series of unlinked structural genes in the nitrogen regulation circuit. NIT2 binding sites in the promoter region of the nit-3, alc, and lao genes are very different in sequence context except for the presence of at least two copies of a GATA core sequence. Changing a single nucleotide of only one of two closely spaced GATA core elements abolished NIT2 binding, demonstrating their importance for NIT2 binding. The effect of altering the number, orientation, or spacing of paired GATA elements and the importance of 5'- and 3'-flanking sequences upon NIT2 binding were examined. Strong binding sites for a NIT2-beta GAL fusion protein appear to contain at least two GATA elements, which can have varied spacing but must be within a certain effective distance, approximately 30 bp, of each other. Surprisingly, the orientation of GATA elements and their flanking sequences have only modest effects upon NIT2 binding.
NIT2是粗糙脉孢菌中的一种全局正向作用调节蛋白，它能激活氮调节回路中一系列不连锁的结构基因的表达。除了至少存在两个拷贝的GATA核心序列外，nit - 3、alc和lao基因启动子区域的NIT2结合位点在序列背景上有很大差异。仅改变两个紧密间隔的GATA核心元件之一的单个核苷酸就会消除NIT2结合，这表明它们对NIT2结合很重要。研究了改变配对GATA元件的数量、方向或间距以及5'和3'侧翼序列对NIT2结合的影响。NIT2-β GAL融合蛋白的强结合位点似乎至少包含两个GATA元件，它们之间的间距可以不同，但必须在彼此约30 bp的一定有效距离内。令人惊讶的是，GATA元件及其侧翼序列的方向对NIT2结合的影响较小。
