Kee K, Niu L, Henderson E
Department of Biochemistry and Biophysics, Iowa State University, Ames 50011, USA.
Biochemistry. 1998 Mar 24;37(12):4224-34. doi: 10.1021/bi9716377.
G4-DNA is a four-stranded structure that is formed by guanine-rich sequences. We report here the purification and characterization of a novel G4-DNA binding protein from Tetrahymena thermophila, designated TGP2. TGP2 was found to preferentially bind to G4-DNA oligonucleotides with adjacent single-stranded domains containing phosphorylated 5' ends and the sequence element, 5'-ACTG-3'. The amino acid sequence of TGP2 has high similarity to dihydrolipoamide dehydrogenase (DLDH) from a variety of species, and TGP2 was shown to have DLDH activity. Purified DLDH from porcine heart and bovine intestinal mucosa were shown to bind specifically to G4-DNA oligonucleotides. On the basis of these results we conclude that TGP2 is DLDH in T. thermophila and suggest that the G4-DNA binding capability of TGP2/DLDH may be biologically relevant.
G4-DNA是一种由富含鸟嘌呤的序列形成的四链结构。我们在此报告从嗜热四膜虫中纯化并鉴定出一种新型G4-DNA结合蛋白，命名为TGP2。发现TGP2优先结合含有磷酸化5'末端和5'-ACTG-3'序列元件的相邻单链结构域的G4-DNA寡核苷酸。TGP2的氨基酸序列与多种物种的二氢硫辛酰胺脱氢酶（DLDH）具有高度相似性，并且TGP2显示具有DLDH活性。来自猪心和牛肠黏膜的纯化DLDH显示出与G4-DNA寡核苷酸特异性结合。基于这些结果，我们得出结论，TGP2是嗜热四膜虫中的DLDH，并表明TGP2/DLDH的G4-DNA结合能力可能具有生物学相关性。
