Werner Erik, Wende Wolfgang, Pingoud Alfred, Heinemann Udo
Crystallography Group, Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13092 Berlin, Germany.
Nucleic Acids Res. 2002 Sep 15;30(18):3962-71. doi: 10.1093/nar/gkf523.
The homing endonuclease PI-SceI from Saccharo myces cerevisiae consists of two domains. The protein splicing domain I catalyzes the excision of the mature endonuclease (intein) from a precursor protein and the religation of the flanking amino acid sequences (exteins) to a functional protein. Furthermore, domain I is involved in binding and recognition of the specific DNA substrate. Domain II of PI-SceI, the endonuclease domain, which is structurally homologous to other homing endonucleases from the LAGLIDADG family, harbors the endonucleolytic center of PI-SceI, which in vivo initiates the homing process by introducing a double-strand cut in the approximately 35 bp recognition sequence. At 1.35 A resolution, the crystal structure of PI-SceI domain I provides a detailed view of the part of the protein that is responsible for tight and specific DNA binding. A geometry-based docking of the 75 degrees bent recognition sequence to the full-length protein implies a conformational change or hinge movement of a subdomain of domain I, the tongs part, that is predicted to reach into the major groove near base pairs +16 to +18.
来自酿酒酵母的归巢内切酶PI-SceI由两个结构域组成。蛋白质剪接结构域I催化从前体蛋白中切除成熟的内切酶（内含肽），并将侧翼氨基酸序列（外显肽）重新连接成功能蛋白。此外，结构域I参与特异性DNA底物的结合和识别。PI-SceI的结构域II，即内切酶结构域，在结构上与LAGLIDADG家族的其他归巢内切酶同源，它包含PI-SceI的内切核酸酶中心，在体内通过在大约35 bp的识别序列中引入双链切口来启动归巢过程。PI-SceI结构域I的晶体结构在1.35 Å分辨率下，详细展示了蛋白质中负责紧密且特异性DNA结合的部分。基于几何形状将75度弯曲的识别序列对接至全长蛋白，这意味着结构域I的一个子结构域（钳状部分）会发生构象变化或铰链运动，预计该部分会深入到碱基对+16至+18附近的大沟中。
