Liao X, Clemens K, Cavanagh J, Tennant L, Wright P E
Department of Molecular Biology, Scripps Research Institute, La Jolla, CA 92037.
J Biomol NMR. 1994 May;4(3):433-54. doi: 10.1007/BF00179350.
The first three zinc fingers (ZF1-3) of transcription factor IIIA (TFIIIA) from Xenopus have been shown to contribute the majority of the binding energy to the intact TFIIIA-DNA interaction [Liao et al. (1992) J. Mol. Biol., 223, 857-871]. We have expressed a 92-amino acid polypeptide containing the three N-terminal zinc fingers of TFIIIA. This three-fingered polypeptide has been isotopically labeled with 15N and 13C in E. coli and purified to homogeneity. Assignment of backbone 1H, 15N, aliphatic 1H and 13C and aromatic 1H and 13C resonances of delta NZF1-3 has been obtained using a combination of single-, double- and triple-resonance multidimensional NMR experiments. The secondary structures for each finger have been determined from NOE connectivities, 3JNH alpha values and chemical shifts. The results show that each finger folds into a canonical beta-sheet-helix zinc finger structural motif, while the linkers adopt an extended structure. The helix between the two histidine ligands in ZF3 is distorted by zinc coordination, to accommodate the presence of four intervening amino acids instead of three as in ZF1 and ZF2.
非洲爪蟾转录因子IIIA（TFIIIA）的前三个锌指（ZF1 - 3）已被证明对完整的TFIIIA - DNA相互作用贡献了大部分结合能[廖等人（1992年）《分子生物学杂志》，223卷，857 - 871页]。我们表达了一种包含TFIIIA N端三个锌指的92个氨基酸的多肽。这种三指多肽已在大肠杆菌中用15N和13C进行了同位素标记，并纯化至同质。使用单共振、双共振和三共振多维核磁共振实验相结合的方法，对δNZF1 - 3的主链1H、15N、脂肪族1H和13C以及芳香族1H和13C共振进行了归属。每个锌指的二级结构已根据NOE连接性、3JNHα值和化学位移确定。结果表明，每个锌指折叠成典型的β - 片层 - 螺旋锌指结构基序，而连接子采用伸展结构。ZF3中两个组氨酸配体之间的螺旋因锌配位而扭曲，以容纳四个插入氨基酸的存在，而ZF1和ZF2中为三个。
