Chiang T Y, Rai R, Cooper T G, Marzluf G A
Department of Biochemistry, Ohio State University, Columbus 43210.
Mol Gen Genet. 1994 Nov 15;245(4):512-6. doi: 10.1007/BF00302264.
NIT2, a positive-acting regulatory protein in Neurospora crassa, activates the expression of a series of unlinked structural genes that encode nitrogen catabolic enzymes. NIT2 binding sites in the promoter regions of nit3, alc and lao have at least two GATA sequence elements. We have examined the binding affinity of the NIT2 protein for the yeast DAL5 wild-type upstream activation sequence UASNTR, which contains two GATA elements, and for a series of mutated binding sites, each differing from the wild-type site by a single base. Substitution for individual nucleotides within 5' or 3' sequences that flank the GATA elements had only modest effects upon NIT2 binding. In contrast, nearly all substitutions within the GATA elements almost completely eliminated NIT2 binding, demonstrating the importance of the GATA sequence for NIT2 binding. Four high-affinity binding sites for the NIT2 protein were found within a central region of the nit-2 gene itself.
NIT2是粗糙脉孢菌中的一种正向作用调节蛋白，它可激活一系列不连锁的结构基因的表达，这些基因编码氮分解代谢酶。nit3、alc和lao启动子区域中的NIT2结合位点至少有两个GATA序列元件。我们检测了NIT2蛋白与酵母DAL5野生型上游激活序列UASNTR（其含有两个GATA元件）以及一系列突变结合位点的结合亲和力，每个突变结合位点与野生型位点仅相差一个碱基。GATA元件两侧5'或3'序列内单个核苷酸的替换对NIT2结合只有适度影响。相比之下，GATA元件内几乎所有的替换几乎完全消除了NIT2结合，这表明GATA序列对NIT2结合的重要性。在nit-2基因自身的一个中央区域内发现了四个NIT2蛋白的高亲和力结合位点。
