Jurica M S, Monnat R J, Stoddard B L
Fred Hutchinson Cancer Research Center, University of Washington, Seattle, Washington 98109, USA.
Mol Cell. 1998 Oct;2(4):469-76. doi: 10.1016/s1097-2765(00)80146-x.
The structure of the LAGLIDADG intron-encoded homing endonuclease I-CreI bound to homing site DNA has been determined. The interface is formed by an extended, concave beta sheet from each enzyme monomer that contacts each DNA half-site, resulting in direct side-chain contacts to 18 of the 24 base pairs across the full-length homing site. The structure indicates that I-CreI is optimized to its role in genetic transposition by exhibiting long site-recognition while being able to cleave many closely related target sequences. DNA cleavage is mediated by a compact pair of active sites in the I-CreI homodimer, each of which contains a separate bound divalent cation.
已确定与归巢位点DNA结合的LAGLIDADG内含子编码归巢内切酶I-CreI的结构。该界面由每个酶单体伸出的凹形β折叠形成，该β折叠与每个DNA半位点接触，导致在全长归巢位点的24个碱基对中的18个上形成直接的侧链接触。该结构表明，I-CreI通过表现出长位点识别能力，同时能够切割许多密切相关的靶序列，从而优化了其在基因转座中的作用。DNA切割由I-CreI同型二聚体中紧密的一对活性位点介导，每个活性位点都含有一个单独结合的二价阳离子。
