Gabrielsen O S, Sentenac A, Fromageot P
Laboratoire d'Ingéniérie des Protéines, Centre d'Etudes de Saclay, Gif-sur-Yvette, France.
Science. 1991 Sep 6;253(5024):1140-3. doi: 10.1126/science.1887237.
The c-Myb protein is a sequence-specific DNA binding protein that activates transcription in hematopoietic cells. Three imperfect repeats (R1, R2, and R3) that contain regularly spaced tryptophan residues form the DNA binding domain of c-Myb. A fragment of c-Myb that contained the R2 and R3 regions bound specifically to a DNA sequence recognized by c-Myb plus ten additional base pairs at the 3' end of the element. The R2R3 fragment was predicted to contain two consecutive helix-turn-helix (HTH) motifs with unconventional turns. Mutagenesis of amino acids in R2R3 at positions that correspond to DNA-contacting amino acids in other HTH-containing proteins abolished specific DNA binding without affecting nonspecific DNA interactions.
c-Myb蛋白是一种序列特异性DNA结合蛋白，可激活造血细胞中的转录。三个含有规则间隔色氨酸残基的不完全重复序列（R1、R2和R3）构成了c-Myb的DNA结合结构域。一个包含R2和R3区域的c-Myb片段与c-Myb识别的DNA序列特异性结合，并在该元件的3'端额外结合十个碱基对。预测R2R3片段包含两个连续的具有非常规转角的螺旋-转角-螺旋（HTH）基序。对R2R3中与其他含HTH蛋白中与DNA接触的氨基酸相对应位置的氨基酸进行诱变，消除了特异性DNA结合，而不影响非特异性DNA相互作用。
