Agre P, Johnson P F, McKnight S L
Howard Hughes Research Laboratories, Department of Embryology, Carnegie Institution of Washington, Baltimore, MD 21210.
Science. 1989 Nov 17;246(4932):922-6. doi: 10.1126/science.2530632.
Both C/EBP and GCN4 are sequence-specific DNA binding proteins that control gene expression. Recent evidence implicates C/EBP as a transcriptional regulator of genes involved in lipid and carbohydrate metabolism. The C/EBP protein binds avidly to the dyad symmetric sequence 5'-ATTGCGCAAT-3'; GCN4 regulates the transcription of genes that control amino acid biosynthesis in yeast, and binds avidly to the dyad symmetric sequence 5'-ATGA(G/C)TCAT-3'. Both C/EBP and GCN4 bind DNA via the same structural motif. This motif has been predicted to be bipartite, consisting of a dimerization interface termed the "leucine zipper" and a DNA contact surface termed the "basic region." Specificity of DNA binding has been predicted to be imparted by the basic region. As a test of this hypothesis, recombinant proteins were created wherein the basic regions and leucine zippers of GCN4 and C/EBP were reciprocally exchanged. In both of the recombinant polypeptides, DNA binding specificity is shown to track with the basic region.
C/EBP和GCN4都是控制基因表达的序列特异性DNA结合蛋白。最近的证据表明，C/EBP是参与脂质和碳水化合物代谢的基因的转录调节因子。C/EBP蛋白与二元对称序列5'-ATTGCGCAAT-3'紧密结合；GCN4调节酵母中控制氨基酸生物合成的基因的转录，并与二元对称序列5'-ATGA(G/C)TCAT-3'紧密结合。C/EBP和GCN4都通过相同的结构基序结合DNA。这个基序被预测为二分的，由一个称为“亮氨酸拉链”的二聚化界面和一个称为“碱性区域”的DNA接触表面组成。DNA结合的特异性据预测是由碱性区域赋予的。作为对这一假设的检验，构建了重组蛋白，其中GCN4和C/EBP的碱性区域和亮氨酸拉链相互交换。在这两种重组多肽中，DNA结合特异性都与碱性区域相关。
