Inoue M, Karita H, Nakayama C, Noguchi H
Sumitomo Pharmaceuticals Research Center, Konohana-ku, Osaka, Japan.
J Neurochem. 1997 Jul;69(1):95-101. doi: 10.1046/j.1471-4159.1997.69010095.x.
Antagonistic mutants of ciliary neurotrophic factor (CNTF) were constructed and their properties characterized. K155A and K155W mutants lost cell survival promoting activity for chicken dorsal root ganglion (DRG) neurons and inhibited the activity of the wild type. However, they retained slight agonistic activity for the survival of rat DRG neurons, indicating there is a difference between chicken and rat cells for receptor recognition around the D1 cap region including K155 residue. The chicken receptor recognizes the D1 cap region more strictly than does the rat receptor. The substitution of F152, which locates at the top of the D1 cap region, was combined with the K155A mutation. A combination of the two mutations gave an antagonistic feature to not only chicken but also rat cells. Both F152S/K155A and F152D/K155A mutants lacked cell survival promoting activity and had an antagonistic effect on rat DRG neurons. The three-dimensional structure of CNTF suggests the following. F152 and K155 bind to the receptor with hydrophobic and electrostatic interactions, respectively. F152 locates close to L156 with a van der Waals contact, and K155 contacts with Q42 through a hydrogen bond. Both interactions play indispensable roles in maintaining the structure around the D1 cap region of CNTF.
构建了睫状神经营养因子（CNTF）的拮抗突变体并对其特性进行了表征。K155A和K155W突变体丧失了对鸡背根神经节（DRG）神经元的细胞存活促进活性，并抑制了野生型的活性。然而，它们对大鼠DRG神经元的存活仍保留轻微的激动活性，表明在包括K155残基的D1帽区域周围，鸡和大鼠细胞在受体识别方面存在差异。鸡受体比大鼠受体更严格地识别D1帽区域。位于D1帽区域顶部的F152的取代与K155A突变相结合。这两种突变的组合不仅赋予鸡细胞，也赋予大鼠细胞拮抗特性。F152S/K155A和F152D/K155A突变体均缺乏细胞存活促进活性，并且对大鼠DRG神经元具有拮抗作用。CNTF的三维结构表明如下情况。F152和K155分别通过疏水和静电相互作用与受体结合。F152通过范德华接触靠近L156，K155通过氢键与Q42接触。这两种相互作用在维持CNTF的D1帽区域周围的结构中都起着不可或缺的作用。
