Qian Y Q, Otting G, Furukubo-Tokunaga K, Affolter M, Gehring W J, Wüthrich K
Institut für Molekularbiologie und Biophysik, Eidgenössiche Technische Hochschule-Hönggerberg, Zürich, Switzerland.
Proc Natl Acad Sci U S A. 1992 Nov 15;89(22):10738-42. doi: 10.1073/pnas.89.22.10738.
The secondary structure of an N-terminally elongated Antennapedia (Antp) homeodomain (HD) polypeptide containing residues -14 to 67, where residues 1-60 constitute the HD, has been determined by NMR in solution. This polypeptide contains the conserved motif -Tyr-Pro-Trp-Met- (YPWM) at positions -9 to -6. Despite the hydrophobic nature of this tetrapeptide motif, the N-terminal arm consisting of residues -14 to 6 is flexibly disordered, and the well-defined part of the HD structure with residues 7-59 is indistinguishable from that of the shorter Antp HD polypeptide (where positions 0, 1, and 67 are methionine, arginine, and glycine, respectively). In vitro biochemical studies showed that the stability and specificity of the DNA binding previously observed for the shorter Antp HD polypeptide is preserved in the elongated polypeptide. These results strongly support the view that the HD is connected through a flexible linker to the main body in the Antp protein and that the minor groove contacts by the N-terminal arm (residues 1-6) in the Antp HD-DNA complex are an intrinsic feature of the DNA-binding interactions of the intact Antp protein.
已通过溶液核磁共振确定了一种N端延长的触角足蛋白（Antp）同源结构域（HD）多肽的二级结构，该多肽包含-14至67位的残基，其中1至60位残基构成HD。该多肽在-9至-6位含有保守基序-Tyr-Pro-Trp-Met-（YPWM）。尽管该四肽基序具有疏水性，但由-14至6位残基组成的N端臂呈灵活无序状态，且7至59位残基构成的HD结构的明确部分与较短的Antp HD多肽（其中0、1和67位分别为甲硫氨酸、精氨酸和甘氨酸）的HD结构无法区分。体外生化研究表明，先前在较短的Antp HD多肽中观察到的DNA结合稳定性和特异性在延长的多肽中得以保留。这些结果有力地支持了以下观点：在Antp蛋白中，HD通过柔性连接子与主体相连，且Antp HD-DNA复合物中N端臂（1至6位残基）与小沟的接触是完整Antp蛋白DNA结合相互作用的固有特征。
