Dathan Nina, Zaccaro Laura, Esposito Sabrina, Isernia Carla, Omichinski James G, Riccio Andrea, Pedone Carlo, Di Blasio Benedetto, Fattorusso Roberto, Pedone Paolo V
Istituto di Biostrutture e Bioimmagini, Via Mezzocannone 6, 80134 Napoli, Italy.
Nucleic Acids Res. 2002 Nov 15;30(22):4945-51. doi: 10.1093/nar/gkf613.
The Arabidopsis SUPERMAN (SUP) gene has been shown to be important in maintaining the boundary between stamens and carpels, and is presumed to act by regulating cell proliferation. In this work, we show that the SUP protein, which contains a single Cys2-His2 zinc finger domain including the QALGGH sequence, highly conserved in the plant zinc finger proteins, binds DNA. Using a series of deletion mutants, it was determined that the minimal domain required for specific DNA binding (residues 15-78) includes the single zinc finger and two basic regions located on either side of this motif. Furthermore, amino acid substitutions in the zinc finger or in the basic regions, including a mutation that knocks out the function of the SUP protein in vivo (glycine 63 to aspartate), have been found to abolish the activity of the SUP DNA-binding domain. These results strongly suggest that the SUP protein functions in vivo by acting as a DNA-binding protein, likely involved in transcriptional regulation. The association of both an N-terminal and a C-terminal basic region with a single Cys2-His2 zinc finger represents a novel DNA-binding motif suggesting that the mechanism of DNA recognition adopted by the SUP protein is different from that described so far in other zinc finger proteins.
拟南芥SUPERMAN（SUP）基因已被证明在维持雄蕊和心皮之间的边界中起重要作用，并且推测其通过调节细胞增殖发挥作用。在这项研究中，我们发现SUP蛋白含有一个单一的Cys2-His2锌指结构域，包括在植物锌指蛋白中高度保守的QALGGH序列，该蛋白能结合DNA。通过一系列缺失突变体，确定特异性DNA结合所需的最小结构域（第15-78位氨基酸残基）包括单个锌指以及位于该基序两侧的两个碱性区域。此外，已发现锌指或碱性区域中的氨基酸替换，包括在体内消除SUP蛋白功能的突变（甘氨酸63突变为天冬氨酸），会消除SUP DNA结合结构域的活性。这些结果强烈表明，SUP蛋白在体内通过作为DNA结合蛋白发挥作用，可能参与转录调控。N端和C端碱性区域与单个Cys2-His2锌指的结合代表了一种新的DNA结合基序，表明SUP蛋白采用的DNA识别机制不同于迄今为止在其他锌指蛋白中描述的机制。
